AD-A240 821 C)Assessment of Short Span Bridge Materials -

by

John R. Brown

A research paper submitted in partial fulfillmentof the requirements for the degree of

Master of Science in Engineering

University of Washington

1990

I Approved by--

Program AuthorizedIto Offer Degree

Date

9i-10899

DtIMEI NOTICE

THIS DOCUMENT IS BEST

QUALITY AVAILABLE. THE COPY

FURNISHED TO DTIC CONTAINED

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Assessment of Short Span Bridge Materials

by

John R. Brown

A research paper submitted in partial fulfillmentof the requirements for the degree of

Master of Science in Engineering

University of Washington .0

1990 .. ,

Approved by---

Program Authorizedto Offer Degree-

Date

University of Washingtion

Abstract

Assessment of Short Span Bridge Materials

by John R. Brown

Chairperson of the Supervisory Committee: Associate ProfessorJimmie Hinze

Department of Civil Engineering

There are approximately 1877 substandard bridges on thefederal aid system and 2193 substandard -bridges off the federal aidsystem in Idaho, Oregon, and Washington, (Secretary ofTransportation, 1989).

In general ,a bridge can be divided into the substructure,superstructure, and decking. The choice of construction materials iscritical for the function and economics of all elements. Wood, steel,and concrete are the principle materials utilized.

Each of these materials has characteristics that add and detractfrom use in short span bridges. A review of current literatureprovided insight into what factors were considered important. Asurvey of how counties have replaced deficient structures in the pastprovides information on materials that will be in demand in thefuture.

This research focused on the criteria that county engineers inIdaho, Oregon, and Washington consider when selecting material fora short span bridge structure.

A survey was prepared and forwarded to county officials inIdaho, Oregon, and Washington to determine past practices andanticipated future trends. A response from 42% of the countiesprovided valuable insight into short span bridges in the Northwest.

One of the most significant facts is that precast concretestructures are predominately utilized for the superstructure anddecking. There are a number of counties that have specialconsiderations that allow for the use of wood and steel structures butthey are the exception. The preponderance of county officialsrecognize precast elements as the most superior material both inperformance and economics.

Table of Contents

List of Figures............................................................................1iList of Tables.............................................................................. ivIntroduction.............................................................................1.Literature Review....................................................................... 3

Wood ................................................................................ 3Steel ................................................................................. 1 3Concrete ............................................................................ 2 1

Previous Research....................................................................... 26Research Methodology ................................................................ 3 33Results..................................................................................... 41Summary................................................................................... 68Conclusions ................................................................................ 72Recommendations....................................................................... 75References ................................................................................. 78Appendix A Cover letter and survey .............................................. 8 2Appendix B Summary of responses..............................................8 7Appendix C SPSS Data Definition File and Data File......................... 134Appendix D List of Respondents................................................... 142Appendix E Summary of Costs for New Bridges ............................. 145

List of Figures

Number Page

1. Prefabricated Steel Rectangular Units ................... 20

2. Precast Element Shapes .............................................. 25

3. Utilization of Materials in the Substructure ...... 54

4. Utilization of Materials in the Superstructure ......... 54

5. Utilization of Materials in the Decking ................... 55

6. Comparison of Required Maintenance ..................... 56

7. Comparison of Material Durability ............................ 56

8. Comparison of Construction Costs ............................. 60

9. Comparison of Material Costs ..................................... 60

10. Comparison of Material Availability ........................ 62

11. Comparison of Speed of Construction ...................... 62

12. Comparison of Design Complexity ............................. 63

13. Familiarity of Materials in the Departments ...... 63

14. Familiarity of Contractors with the Materials ..... 65

15. Comparison of the Availability of Funding ............ 65

16. Relative Aesthetic Value of the Materials ............... 66

iii

List of Tables

Number Page

1. Number of Counties that Receive Federal, State,and Local Funding for Bridge Replacement ...................... 43

2. Number of Deficient Bridges by State .................................. 46

3. Number and Percentage of Bridges Constructed or

Under Construction (1988-1990) by Length .................... 47

4. Priciple Construction Materials for New Bridges ............. 49

5. Average Bridge Replacement Costs in Dollars ................... 51per Square Foot of Bridge Deck

6. Estimated Number of Material Suppliers ............................. 52

7. Averages of the Selection Factors for ................................... 56Cast-in-Place, Precast, Steel, and Wood

8. Average Responses for Substructure andSuperstructure Material Selection Factors .......................... 66

iv

ACKXNOWLEDGMENTS

The author wishes to extend a sincere thankyou to Professor Jimmie Hinze for hisassistance in the preparation of this researchpaper.

DEDICATIONA special note of appreciation goes to my wife,whose support and encouragementthroughout this project enabled me to see thelight. This research paper is dedicated to her.

vi

lntroduciien

Because of the publicity generated by bridge failures and the

deteriorating condition of the nation's bridges, Congress passed the

1968 Federal Highway Act. This statute mandated that all bridges on

the federal-aid system receive a biannual inspection and that the

Federal Highway Administration maintain records of these

inspections. With passage of the Surface Transportation Assistance

Act (SAA) of 1978, the biannual inspection requirements for bridges

were expanded to include all bridges not on the federal aid system

(TRB Special Report 202, 1984). In 1987 the Surface Transportation

and Uniform Relocation Assistance Act (STURAA) extended the

Highway Bridge Replacement and Rehabilitation Program (HBRRP) to

low water crossings (Secretary of Transportation, 1989). As of June

1988 there were 98,526 structurally deficient bridges and 62,639

functionally obsolete bridges off the Federal-aid system (Secretary of

Transportation, 1989).

Short span bridges are not as visible to the public as the

highway bridges on the Federally funded road system. However

these bridges on the secondary roads play a vital role in this

country's overall transportation system. The number that require

repair or ieplacement represents a significant expenditure of public

funds.

Out of the total of 7791 off the federal-aid system bridges in

Idaho, Oregon, and Washington approximately 1017 are structurally

deficient and 1176 are functionally obsolete (Secretary of

Transportation, 1989). Structurally deficient bridges are either

closed to traffic or are load posted for loads less than considered

adequate for the anticipated level of traffic. Bridges are classified as

functionally obsolete typically because the bridge geometry is

deficient for the intended use. Examples of functionally obsolete

bridges are those with poorly aligned roadway approaches, narrow

roadway widths, or hydraulic openings that are too small. In Idaho

40% of the bridges off the federal-aid system require replacement

while in Oregon the percentage is 24% and in Washington 22%. Many

of the bridges off the federal aid system are county bridges with

spans of less than 120 feet.

The engineers responsible for specifying replacement

structures have many variables to consider for each design.

Numerous materials are available to meet the design parameters.

Bridge structures can be constructed of any of the common

construction materials: wood, steel, and concrete. Some materials

have thousands of years of history such as the masonry arch and log

bridges while others have relatively more recent histories such as

the prestressed prefabricated concrete bridge. All of these materials

and systems have their place for a bridge structure. This research

will focus on the criteria that county engineers consider when

selecting material for a short span bridge structures.

Literature Review

A review of the literature provides insight into the factors

considered for bridge selection. Many articles have been published

highlighting how various state and county agencies have approached

their bridge replacement programs.

In general a bridge can be divided into the substructure and

superstructure. The substructure is that part of the bridge that

transmits the loads on the bridge to the bearing soil. The

substructure iacludes the tootings, breastwal's or backwalls,

wingwalls, bridge seat, piling, and bents (Ritter, 1990).

The superstructure is what a layman normally considers "the

bridge" and typically is the most visible part of the bridge. It

consists of the parts that cross the clear span such as: the stringers,

railings, guardrails/parapets, and decking. The types of

superstructures most common in short spans today are the beam,

deck slab, truss, and arch (Ritter, 1990).

The choice of construction materials is critical for the function

and economics of all elements. Wood, steel, and concrete are the

principle materials utilized in the substructure, superstructure, and

decking.

Wood

Of the three materials considered, wood by far has the longest

history as a bridge material. The earliest forms of "bridges" were

logs that naturally fell across clearspans allowing man to cross

otherwise impassable areas. Man has modified these early

structures to permit greater clear spans and ;,creased loads.

4

Timothy Palmer a civil engineer from Newburyport,

Massachusetts built a 2362 feet long by 38 feet wide wooden bridge

7 miles north of Portsmouth, New Hampshire in 1794 (Ritter, 1990).

The bridge consisted of pile trestles for the approach spans and

three arched trusses. Palmer is also credited with constructing the

first Ameri,an covered wooden bridge ove- the S4,huylkill River in

PLiladelphia tn 1806. Tis started a trend wh*ich resulted in

approximately 10,000 covered bridges being built in the United

States between 1805 and 1885 (Ritter, 1990).

This same century saw the rapid growth of the railroads and

the resultant requirements tor bridges at river crossings. Wood was

the logical choice as a building material due to its abundance and the

availability of the skilled labor necessary for bridge erection . Truss

bridges and trestle bridges were the predominant wood designs

during this period.

Even as wood bridge construction reached its zenith in number

of structures built, other materials were being considered. Irons

were begun to be utilized do to superior shear strength as compared

to wood. The first metal bridges were cast iron. However wrought

iron structures started to dominate bridge structures by the mid

19th century do to higher shear strengths. By the end of the 19th

century steel had replaced wrought iron as the primzry bridge

material. Additional de velopments in steel production resulted in

ever more economical structures. "By the mid-1930's, steel was less

expensive than wood on a first-cost basis and took the lead as the

primary bridge material" (Ritter, 1990).

I 5

Wood has many properties that make it a valuable material in

modern bridge construction. Wood is relatively light per unit of

length in comparison to concrete. Wood weighs, depending on

species, from 35-60 lbs per cubic foot. Structural lightweight

concrete, often used is long bridge decks, is 90-120 lbs per cubic foot

of material. The less weight per volume results in wood

superstructures with lower dead loads. This factor makes it possible

and more economical to utilize smaller substructures. For an

entirely new bridge this means savings due to reduced material and

construction costs. There are examples in which wood was the most

economical alternative for replacement of an substandard bridge

because the light dead load allowed use of the existing substructure

(Verna, 1983).

Lighter members also enhance the erection of the structure,

since smaller construction equipment may be utilized during

erection. This is especially important in isolated areas where

equipment availability is very limited. Transportation of lighter

structural members is also easier and more economical. This factor

becomes more critical for more isolated construction sites.

Wood lends itself to bridge systems since elements may be

pre-fabricated off site. The relatively light material weight makes is

I possible to transport large pre-assembled components. The

advantage of this is that a large part of the work for the bridge

actually takes place off site in a controlled environment. If

prefabrication of the components was correct only assembly is

required on site. This speeds erection time with resultant reduction

in construction costs (Williamson, 1972)

I 6

Assembly of a wood bridge often requires only semi-skilled

I labor. This is especially true when bridges consist of prefabricated

components that are cut to required dimensions and pre-drilled for

connections. Often times complete assembly only requires simple

I tools such as torque wrenches.

The resistance of wood to chemicals and corrosive materials

has increased interest in its use in bridge construction. The effects of

roadway chemical deicing agents on steel and concrete bridges has

been shown to reduce the life expectancy of these structures.

Barnhart (1987) has noted that nail laminated timber decks in Ohio

have lasted an average of 30 - 40 years with minimum maintenance.

However, many reinforced concrete decks showed signs of spalling

after only 5 or 10 years of attack by deicing salts and required

"considerable patching" within 20 years (Barnhart, 1987). As a

result the concrete reinforced decks had an average expected life of

30-35 years (Barnhart, 1987). Similar findings have been noted on

the 1700 bridge system of Allegheny County, Pennsylvania (Verna,

1980). In some parts of the country the deterioration to concrete

decks is so severe that replacement is required after only 15 years

(Transportation Research Board Special Report 202). Timber is often

an economical alternative solution for deteriorated bridge materials

in those sections of the country (Verna, 1983).

Wood is a renewable resource. It is a natural material that

blends well with its surroundings, presenting an aesthetically

appealing structure. Less energy is required to produce theImaterials and to erect a wood structure than one built of cast in place

concrete (Weyerhaeuser, 1980). The energy required to produce a

7

cunstruction material may become a major factor in economical

considerations for bridge material selection as it did in the early

1970's.I' Wood does have limitations that have contributed to its

decline as a bridge material. The foremost of these is its

susceptibility to decay. It is an organic material and is a food source

for a number of decay fungi, microorganisms, wood boring insects,

and marine organisms (Muchmore, 1984). This is especially true if

the untreated wood is exposed to the elements and allowed to get

wet. The functional life of wood is significantly increased if it is kept

dry. This was the purpose of the covered bridges of the 19th

century. The covered structure was built to protect the timber

structure from the deteriorating action of the elements.

Today wood is protected by pressure treating with

preservatives such as the oil based: creosote, pentachlorophenol, and

copper naphthenate or one of a number of waterborne preservatives

(Ritter, 1990). These pressure treatments, if properly performed and

if the protective envelope is maintained, can increase the life of a

wood structure by a factor of 5 to 10 (Erikson, 1989). Use of some

of the chemicals for pressuring wood is becoming more difficult as

concern arises over their impact on humans and the environment.

These is especially true for pentachlorophenol which has been placed

on the EPA list of restricted-use chemicals. This requires that the

applicator pass a test administered by the controlling state

authorities (Ritter, 1990). Preservation is rarely accomplished in the

same location where the member was sawn or fabricated. This

8I

increases the time required for delivery which is often greater than

that for a steel or concrete beam.

The strength of wood is dependent on a number of factors.

i Three of the most important are species, grade, and moisture content.

Naturally occurring knots are considered defects and reduce the

strength of the wood. Moisture content over the fiber saturation

* point also reduces its strength.

Dimensional stability is another characteristic that directly and

I indirectly can have negative effects on bridge structures. The

* dimensions of wood members are effected in all three axes by

moisture content and to a lesser extent by temperature. Sawn

lumber will expand and contract depending on moisture content of

the wood. The amount of expansion and contraction will vary for the

three axes depending on axis orientation to the wood grain. The

differential volumetric changes can result in checks and cracks in the

wood and contributes to the loosening of mechanical connections.

Mechanically connected timber structures resist impact loads

by transferring the load from the point of impact to adjacent parts

I (Hale,1977). The elastic nature of wood and the characteristic of

*] transferring impact loads has had an negative effect on the

utilization of wooden bridges. In particular it has prevented the

incorportation of an economical wooden guard into the AASHTO

bridge specifications. Lightweight wooden guardrails have been

successfully statically load tested in accordance with AASHTO

standards. However crash testing for complete AASHTO acceptance

has not been performed. Although wooden rail systems meet the

performance criteria for rail systems by containing a vehicle upon

I 9Iimpact, the defection of the wooden rails is not within current

IAASHTO standards (TIBIRC Crossings, 1990).

Wood members must be deeper than steel or concrete in order

to carry the same design load. The hydraulic opeing of the bridge

may be reduced significantly which is unacceptable if flood

conditions are critical.

The engineering community relationship with wood structures

is not as intimate as that for steel or concrete. Most college curricula

emphasize the use of steel and concrete as structural materials but

I consider wood a material for light framing, as in house construction.

Although sawn lumber and even rough logs are still utilized on

I low volume roads, most wood bridges today are constructed of

engineered wood products. The positive characteristics of wood have

been enhanced and the negative characteristics mitigated by

pressure treated engineered wood products such as glued laminated

(glulams) and laminated veneer lumber (LVL).

Glued laminated members are laminations of 1 to 2 inch

nominal strips of wood, oriented so that the grains of all the

laminations are parallel. The laminations are positioned according to

the intended use of each member. The stronger sections of wood are

in the most critical cross sectional area. In the case of a beam, lower

grade laminations are placed on the neutral axis and higher grades

are placed on the outside laminations. The laminations are bonded

I together with a waterproof adhesive. These forms of engineered

wood members have been in use since the 1940's (Erikson, 1989).

Laminated veneer lumber, as the name indicates, is produced

I from laminating veneers of wood in much the same way that

I

1 10

plywood is produced. However, unlike plywood where the wood

grains in the adjacent veneers have a perpendicular orientation, LVL

veneer grains are all in a parallel orientation.

These engineered wood products provide a number of

advantages over sawn lumber. Defects that naturally occur in wood,

such as knotholes, are not concentrated in one area in engineered

wood. They can be distributed throughout the member and placed in

areas that will not be subjected to high stress, such as the neutral

axis of a beam.

The laminations and veneers are dried to a uniform moisture

content prior to fabrication. This prevents much of the dimensional

problems noted earlier and allows for greater strength ratings.

Glued laminations and laminated veneer lumber can be

manufactured into lengths limited only by the available jig of the

fabricator, or for pressure treated members by the size of the

treatment cylinder. This is especially critical since sawn lumber is

not often available in the sizes required. Glued laminations in excess

of 120 feet have been fabricated. Laminated veneer beams have

practical limits of about 80 feet (Erikson, 1989).

* Creosote treated wood is noted for its use in bridge abutments

and bents. The abutments are the structure that support the ends of

the bridge and hold back the roadway embankment material. Bents

are the intermediate supports for multispan bridges. Wood

abutments commonly support the superstucture either by a post or

pile structure (Ritter,1990). Sawn lumber or glued-laminated posts

transfer the superstructure loads to buried spread footings that are

typically made of concrete (Ritter, 1990). Horizontal planks can be

placed behind the wooden posts to form breastwalls and wingwalls

which hold back the embankment material. Piles are driven in areas

where soils cannot support a buried footing. Pile abutments transfer

- the superstrcture loads through wood piles vice posts on spread

3 footings. Like post abutments pile abutments can be used to elevate

the superstructure (Ritter, 1990), and with the attachment of

* horizontal planks hold back the embankment material.

Wood use in bridge superstructures is almost exclusively restricted

I to clear spans under 120 feet. The trestle or truss systems utilized in

the 19th century are not the most common designs of wood bridges

today. Wood superstructures usually are glued laminated simple

* span stringers with either a transverse glued laminated deck or nail

laminated sawn lumber deck.

Glued laminated deck panels are 3 1/8 inches or thicker

depending on the spacing between stringers (Weyerhaeuser, 1980).

The panels are typically three to five feet wide with lengths set to

meet the bridge deck width requirements. The deck panels may be

placed with or without any connection between panels. Dowel

I connections are typically used between panels if the roadway surface

is finished with a bituminous wearing coat to provide for better

wheel load transfer (Ritter, 1990). Both types of deck panels are

* often utilized with steel stringers in lieu of the glued laminated

stringers (NCRP Report 222, 1980).

Another form of all wood superstructure is the longitudinal

deck glued laminated bridge. In this design the deck panels run in

the longitudinal direction (the same axis as the clear span and the

3roadway direction) and support the loads without any additional

I

S12

longitudinal members. Transverse beams are added to tie the

longitudinal panels together and provide distribution of wheel loads.

The advantage of this design is that it has less depth and provides

greater space between the bottom of the superstructure and the

water crossing. This increases the hydraulic opening for flood levels

(Weyerhaeuser, 1980).

Prior to the introduction of glued laminated decks, sawn

lumber planks and nailed laminated decks were in common use.

Sawn lumber planks are pieces of dimensional lumber laid flat and

nailed either transversely or longitudinally to the underlying

stringers. Nail-laminated decks are made up of dimensional lumber

placed on edge so that the wider face is in a vertical orientation. The

pieces of lumber are mechanically laminated with nails and then

nailed to the stringers . Such decks have lasted as long as 40 years.

However, their use, even on roads with light average daily traffic

(ADT), has declined significantly. Both decks are not suitable for

bituminous wearing surfaces. Loosening of the nails occurs due to

vibration, localized wheel loads, and moisture content variations

which result in dimensional changes (Peterson, 1987). The loosening

of the connections allows individual lumber pieces to deflect beyond

the tolerance of the wearing course.

Stressed laminated timber decks are being emphasized by the

timber industry. A stress laminated timber deck is similar to a nail

laminated deck in that sawn lumber planks are laid on edge and

laminated together. However, the planks are held together by the

compressive forces of transverse posttensioned high strength steel

rods (Sarisley, 1990). This form of decking eliminates nail

13

laminations which can loosen and also provide an avenue for

moisture penetration.

The stress laminated deck system was originally developed in

Ontario, Canada and has been included in the Ontario Highway Bridge

Design Code since 1983 (Ritter, 1990). The American Association of

State Highways and Transportation Officials have adopted a "Guide

Specification" for stress laminated timber decks pending approval of

the full membership (TBIRC Ritter, 1990).

Woods characteristics and availability make it a very useful

building material. It was utilized extensively in this country in the

19th century as a bridge material. Some of the characterisiics that

have detracted from its continued prominent position as a bridge

material have been mitigated by modern wood engineering

techniques. Glued laminated and laminated veneer lumber have

resulted in stronger structural members that can be produced in long

spans. Pressure treatment has increased the service life of most

bridges by preventing attack by decay organisms. The extensive use

of corrosive de-icing salts with the resultant deterioration of concrete

and steel has sparked a renewed interest in the use of wood in

bridge structures. Wood appears to be a viable option for short span

bridges on the secondary road system.

Steel

The shift to the use of steel as the primary material in bridge

superstructures occurred in the early 20th century. The railroad

expansion era had a profound influence on bridge construction

(Ritter, 1990). Speed of erection was a major consideration in bridge

14

design and material selection. Initially wrought iron trusses were

the most common metal bridges (Heins and Firmage, 1979).

However, the heavy train loads imparted on short span bridges

required members with high shear strength. The large number of

timber and wrought iron bridge failures in the latter part of the 19th

century necessitated the use of a stronger material (Heins and

3 Firmage, 1979).

Steel became readily available with the development of the

I Bessemer process in the early 19th century. This process removed

impurities from molten pig iron producing steel. Heins and Firmage

(1979) state that the properties of steel are dependent on: "... kind

and quantity of alloying elements, the amount of carbon, the cooling

rate of the steel, and the mechanical working of the steel such as

rolling and stressing." Modern steel mills can produce many

different grades of steel. The choice of steel for a bridge depends on

its intended use and availability from the mill.

Today, steel is one of the premier construction materials. The

following characteristics show some of the advantages and

drawbacks to the use of this material in short span bridges.

Strength is the principle characteristic which makes steel a

very useful bridge material. Steels most commonly used in

contemporary bridge construction have minimum yield points of

36,000 psi (A36), 50,000 psi (A572 G50), 50,000 psi (A588), and

90,000 to 100,000 psi (A514) (U. S. Steel, 1986).

Steel is a predictable and familiar engineering materiai

generally classified into one of three categories: carbon steels (A36),

high-strength low-alloy steels (A572 and A588), and heat-treated

I

15

alloy steels (A514) (Heins and Firmage, 1979). Designers know the

characteristics of a particular grade of steel and can accurately

predict its behavior in a variety of conditions. Familiarity of the

material is fostered by the extensive exposure in engineering

curriculums to the application of steel in construction.

The use of steel is very prevalent in all areas of the

construction industry. Fabricators and erectors are well versed in

the methods of steel construction. This makes steel a logical choice

for a public bridge project that will be bid upon and constructed by a

private contractor.

It is possible to produced steel in a variety of shapes. Standard

structural shapes are available that are very suitable for short span

bridge construction. Godfrey (1975) noted that prefabricated steel

bridges in the Pacific Northwest are inexpensive due to their

simplicity and minimum field work...". As much as possible, steel

bridge structures are prefabricated prior to delivery to the site. This

results in reduced construction time, shorter duration of road

closures, and less construction costs.

All materials have limitations in use and steel is no exception.

One of the principle characteristics of steel that detracts from its use

is corrosion. The combination of moisture and air cause the oxidation

of the steel resulting in the formation of ferric oxide (rust). This

process can become sufficiently severe that the structural integrity

of some members will be compromised. This process is exacerbated

with the use of de-icing salts. In order to prevent corrosion, steel

surfaces must be protected with a coat of paint which adds to the

total life cycle costs of bridges.

16

The steel industry produced a low-alloy steel, A588, in the

early 1960's. This steel oxidized like any other unprotected steel

when left exposed to the elements. However, unlike other steels the

initial thin ferric oxide film was supposed to "...remain tight to the

steel preventing any moisture penetration and further oxidation"

(Heins and Firmage, 1979). However, this has not always been the

case as determined by examining the approximately 2000 A588

bridges constructed in the United States (Robison, 1988).

A588 requires a specific combination of moisture and some

airborne contaminants to create the protective film (Robison, 1988).

If the steel is not subjected t- Ohe correct combination it may not

create the protective film and continues to corrode. Gary Kasza of

the Federal Highway Administration's Portland, Oregon office did a

survey in 1986 of 11 Washington state bridges constructed of A588.

He concluded that it should not be used in wet climates (Robison

,1988). It appears that this steel is not corrosion free in the

relatively wet western counties of Washington and Oregon.

Material availability and cost are two other factors that have

reduced the use of steel in the Northwest. Although prefabrication

has reduced the initial costs of steel bridges the initial costs of other

materials have become even more competitive. Generally there are

more concrete plants and precasting yards than steel mills in the

northwest. Local raw materials are available and utilized to produce

concrete. This reduces production and transportation costs usually

making the initial material cost of concrete more attractive.

Short span steel bridges have gone through a number of

evolutions before arriving at the common designs in use today. At

I 17

the end of thel9th century, railroads started to use steel plate

girders for short span construction. These girders could be

prefabricated and then shipped by rail to the construction site and

lifted into place by mobile steam powered railway cranes (U.S. Steel,

I 1986). The superior strength of steel in comparison to other common

materials such as wood or wrought iron made it a highly aesired

jmaterial. With the fabrication of plate girders and the heavy lift

capability of mobile steam powered railway cranes steel plate girder

I bridges became a common railroad bridge design.

IThf, early steel highway bridges consisted of through and pony

trusses. Many early bridge sites weie 'ery isolated with narrow

I roads. Heavy lift construction equipment was not available, which

necessitated small, easy to handle bridge components (U.S. Steel,

1986). Truss systems were the dominant design because they could

be constructed on site with angles and plates riveted together. Other

advantages of the through and pony truss were that they required a

"...minimum increase in approach grades..." and provided maximum

clearance between the bridge structure and potential flood levels

(U.S. Steel, 1986). The deck system typically was a nail laminated

wood deck. These designs were not an efficient use of material and

resulted in high dead loads. However, the light live loads and

inexpensive fabrication costs made them a feasible and highly

economical design at the turn of the century (U.S. Steel, 1986).

In the early 1920's the first wide-flange rolled beams capable

of being utilized in bridge superstructures became readily available.

The rolled beams could be assembled faster than plate girders,

making them more economical. The increased use of rolled beams

was facilitated by the developmei., of new heavy lift construction

equipment and more accessible bridge sites (U.S. Steel, 1986).

Deck systems of either reinforced concrete or timber became

widely utilized in conjunction with the rolled beam stringers. Simple

span designs consisting of rolled beams with a deck system were in

use in the late 1930's " .. for spans up to about 70 feet and were

sometimes used for spans up to 90 feet" (U.S. Steel, 1986). This

signaled the end of th- through truss as the predominant design in

steel briut,. Today steel trusses are predominantly utilized for

temporary bridges or in military applications (Sprinkel, 1985).

Lessons learned about welding during the second world war

1 were applied to bridge construction in post war Europe and then in

th e United States. Welding resulted in a more efficient use of

I materials which resulted in smaller dead loads and more economical

structures (U.S. Steel, 1986).

Use of prefabricated steel bridge components occurred during

I the 1950's. Prefabrication increased in the steel industry due to the

competitive nature of construction (Elasser, 1972). The use of

I prefabricated bridge components reduced on site construction time,

decreasing labor and equipment costs and bridge closer times.

Today steel continues to be a major component in bridge sub-

I structures and superstructures. One of the more common

superstructures on the secondary road system are steel stringers

with concrete decks (Better Roads, 1971; Sachse and Willis,1973;

NCHRP Report 222, 1980). These structures can be simple or

continuous spans. For span lengths of 40 ft and less non composite

I beams of A36 are very common (U.S. Steel, 1986). Up to 80 ft. wide

U 19

Iflange beams have been used economically (U.S. Steel, 1986; NCHRP

Report 222, 1980; and Taly and GangaRao,1976).

Welded plate girders of composite construction are

recommended in the U.S Steel Design Handbook for simple spans

3 greater than 80 ft. In composite construction the concrete deck slab

is connected to the steel stringers and becomes an integral part of

the beam. It not only functions as the bridge deck but also acts with

the steel stinger in carrying bridge loads.

I As mentioned previously most bridge elements are

prefabricated. These components come in a variety of shapes and

sizes. Prefabricated T-shaped units up to 80 ft. long and 6 ft. wide

can be used in multiple spans from 50 to 110 ft (NCHRP Report 222,

1980). Rectangular units either 39 ft. 4 in. or 19 ft. 8 in. long are

I combined for different site conditions and roadway widths

(see Figure 1) (NCHRP Report 222, 1980). Spokane Culvert Company

produced some 200 bridges from 1968-1975 consisting of plate

girders topped with steel bridge planks. They were used for spans

up to 100 feet in county and U.S. Forest Service bridges (Godfrey,

1 1975). Armco Steel Company of Ohio produced a similar design

utilizing rolled sections for spans up to 50 ft. Up to 1975, Wallowa

County, Oregon had constructed 150 of these steel structures utilizing

its own crews (Godfrey,1975).

A review of the literature reveals that steel is primarily

utilized in the superstructure. However examples are available of

the use of steel in the substructure and decking. Steel H beams can

be driven as piles for intermediate bents and abutments with steel

II

20

St ructra T..o*Transverse Roadway Rib

/

IStoat Plot* (Covered with 1 '14

thick modified asphalt wearing surface.)

PREFABRICATED STEEL RECTANGULAR UNITS

I

II

II

U 21

Isheet piling retaining the embankment material (Better Roads, 1971;

and NCHRP Report 222, 1980).

Steel decks usually are either steel grid or orthotropic plates.

I The primary advantage of these deck structures are that they are

light and easy to install (Spinkel, 1985). However the expense of

these decks normally do not justify their use in short span

structures, particularly in areas of light traffic.

The long span corrugated arch is a system that can be

I considered both the substructure and superstructure. This system

can be utilized for spans from 20-60 feet (NCHRP Report 222, 1980;

and Perin, 1973). The use of this system is highly dependent on

3 existing soil conditions and available fill material (Godfrey, 1975).

Steel has a long history of use in bridge construction in this

I country. It is a very familiar construction material. Certain

limitations have to be considered prior to and during its use in

bridge structures. Today, prefabricated bridge elements are the

standard method of steel bridge construction. Rolled shapes and

plate girders are utilized in prefabricated components depending on

U span length, design, and fabricator. These steel superstructures have

been a very viable option in the past in counties in the northwest.

Concrete

* Prior to the Roman empire mortar was used in construction

However modern forms of reinforced concrete were not utilized until

3 the late nineteenth century (Heins and Lawrie, 1984). Reinforced

concrete bridge structures were pioneered in Europe by Hennebique

I of France (Heins and Lawrie, 1984).

I

22

As early as 1886 prestressed concrete was being investigated.

However, it was not until 1926-1928 that the control of the loss of

the prestress with high-strength steel made the application of

prestressed concrete members practical in construction (Heins and

Lawrie, 1984). The use of prestressed concrete girders in bridg.

construction started in the U.S. 40 years ago with the construction of

the Walnut Lane bridge in Philadelphia in 1950 (GangaRao and Taly,

1976). The use and acceptance of precast prestressed concrete in

bridge structures has increased as reported by Godfrey (1975) and

Sprinkel (1985).

Concrete, in particular Portland Cement Concrete, is one of the

premier bridge construction materials. Cast-in-place bridge

structures built 65 years ago utilized mix designs that developed

I compressive strengths of 2000 psi (Pfeifer, 1972). Today modern

design mixes, placement techniques, and curing can easily produce

high-quality, high-strength concrete of 10,000 psi and greater. This

* permits designs with long clear spans eliminating intermediated

piers and bents. Some precast prestressed sections are capable of

180 foot clearspans (Prestresscd Concrete Institute, 1980). The

strength of concrete in action with prestressing steel can produce

beams with very low depth to span ratios (Prestressed Concrete

Institute, 1980). This important characteristic result in maximum

hydraulic openings.

In addition to high compressive strength concrete has many

other characteristics that make it a desirable construction material.

The majority of the weight and volume of concrete is composed of

aggregates which typically are produced locally resulting in reduced

23

production costs. Concrete can be produced in a variety of strengths

and weights to suit project requirements. Lightweight concrete can

be produced for bridge decks that has a dead load of 85 to 115

pounds per cubic foot (Kosmatka and Panarese, 1988). Fluid concrete

is moldable to many shapes providing flexibility in bridge design.

Properly mixed and placed concrete is a highly durable material with

little fatigue due to its high strength in comparison to low bridge

loads. Properly chosen aggregates provide a hard, skid resistant

I wearing surface. Concrete resists attack by many corrosive

chemicals. The thermal properties of properly cured concrete are

desirable in bridges, resisting fire as well as freeze thaw cycles.

Little to no maintenance is required of concrete bridges. Concrete

does not require painting and will not require patching unless some

I chemical attack produces spalling or cracking.

Problems can develop with any concrete bridge. Poor mix

design, improper components, and incorrect placement, finishing,

*and curing all will contribute to an unsatisfactory concrete bridge.

Cracking due to shrinkage during curing or due to high fatigue will

I allow the penetration of water resulting in reduced service life.

Concrete can be susceptible to expansion due to attacks by sulfites

present in water runoff or other sources. An excess of trapped water

in concrete will result in popping and spalling during freeze thaw

cycles. Highly permeable concrete may allow excess moisture to

penetrate to reinforcing steel. The resultant rusting and expansion of

the steel can result in spalling and other deterioration. These attacks

are exacerbated by the use of road de-icing salts (Barnhart, 1987).

II

24

Concrete construction is very dependent on weather conditions.

Heavy rains will produce complications during the placement,

finishing, and curing of concrete bridges. Cold weather is another

eivifoinntal conditioai that caa hamper if not prevent concrete

bridge construction.

Many of the problems noted with concrete can be mitigated or

eliminated in the controlled environment of a precast yard. Exact

proportioning of mixtures, combined with uniform mechanical

consolidation, and steam curing result in high strength, highly

impermeable uniform bridge components.

Precast elements are utilized in all the components of a bridge.

Concrete piling is very common for substructures. These can be

formed and poured on site or precast elements. Precast yards

produce abutments and wingwalls that can reduce on site labor

(Prestressed Concrete Institute, 1980).

Precast superstructural elements come in many different

shapes depending on span requirements and the available forms in

local precast yards (see Figure 2). Many of these shapes include an

integral decking system. Solid deck slabs are utilized in spans less

than 30 feet and voided slabs can span up to 50 feet with the

standard AASHTO HS-20 load (Prestressed Concrete Institute, 1980).

Channel sections and multi-stemmed sections can be utilized for

intermediate spans from 20 to 60 feet while double stemmed

sections can span 60 feet and more (Prestressed Concrete Institute,

1980). For longer spans exceeding 100 feet box girders, I-girder

sections, single stem sections, or bulb tee sections are available. The

bulb tee section is very common in Washington, Oregon, and Idaho

25

I ZSpread box Channel

Box Slab

24

Bulb tees

I ~ ~~AASHO -PCI _ __

Types 1-4 0 9 9 Voided slab

AASHO-PCI Box

Types 5-6

IL J Tee D 7 Double box

Composite sections Noncomposite sections

Figure 2. Precast Concrete moment Shapes

(Heins and Lawrie, 1984; Prestessed Concrete Insitute, 1980)

IIIII

26

(Godfrey, 1975). It is possible to have clear spans up to 180 foot

with bulb tee sections (Prestressed Concrete Institute, 1980). As

mentioned all of these sections have an integral bridge deck or can

I have a cast-i -place deck placed on top. This improves the bridges

* strength and provides a different wearing surface than the precast

element.

* Precast elements have many advantages over cast-in-place

concrete structures. The most important is the more consistent

I quality of the final concrete that results from the controlled

conditions of the precasting yard. In a precasting yard it is also

possible to prestress structural elements which provides additional

strength permitting longer clear spans. Precast elements can be

fabricated and assembled in a shorter period of time than

I cast-in-place structures.

Modern concrete has been refined to make it a superior bridge

material. It has many characteristics that highlight its value in

bridge construction. If not properly constructed on site or properly

prefabricated in a precasting yard concrete bridge structures may

have degraded performance that can be inferior to other materials.

Typically this is not the result and concrete construction results in

superior bridge structures. This is especially true if precast,

prestressed elements are utilized.

Previous Research

A poor bridge management program including negligent

inspections resulted in the collapse of the Silver Bridge in West

Virginia on December 15, 1967 killing 46 people. The actual cause of

27

the disaster was the failure of one of the structural eyebars due to

the joint action of stress corrosion and corrosion fatigue" (Ross,

1984). This disaster has had a ripple effect on state and county

bridge programs that continues to this day. Actions in Congress

include passing legislation aimed at identifying and rectifying the

problems with the nation's bridge infrastructure. Congress initiated

the Special Bridge Replacement Program (SBRP) in 1970 authorizing

$816.5 million over eight years. Since that first action there have

I been three modifications to the legislation. Most recently the Surface

Transportation and Uniform Relocation Assistance Act (STURAA) of

1987 extended the Highway Bridge Replacement and Rehabilitation

Program (HBRRP) authorizing $1.63 billion annually until the end of

fiscal year 1991 (Secretary of Transportation, 1989).

I The HBRRP allows for federal payment of up to 80 % of the

costs of a bridge project. Money is allocated to states by the FHWA

in accordance with an apportionment factor. The apportionment

* factor is the ratio of the states needs compared to the national needs.

States needs are defined by a standard sufficiency rating assigned to

the bridges on the national bridge inventory. The sufficiency rating

is based on the most recent AASHTO "Manual for Maintenance and

Inspection of Bridges". Bridges are evaluated for three general

categories and relative percentages: structural adequacy and safety

(55%), serviceability and functional obsolescence (30%), and

essentiality for public use (15%) (Secretary of Transportation, 1989).

The greater the number of bridges with low sufficiency the greater

the needs of the state.

28

Funding and emphasis on the national level has generated

research into all aspects of bridge programs. Some of these reports

provide insight into present practices and utilization of materials in

short span structures. In April 1974 GangaRao and Taly (1976)

conducted a national survey of short span bridges (75 feet and less).

A questionnaire was sent to the "Chief Bridge Engineers" of all 50

stateF. Useful information was obtained from Idaho and Oregon but

only general information was included about Washington state since

it was not one of the 46 respondents.

The survey revealed no national standard in bridge

construction although the majority of states utilized AASHTO and the

FHWA standards as "guiding criteria" for bridge widths. The

predominate form of bridge decks were cast-in-place concrete.

Timber decking was the only other form of bridge deck mentioned.

It was utilized under "special conditions" in Louisiana, Minnesota,

and Wisconsin despite its "high material costs" (GangaRao and Taly,

1976). The advantage of the timber decks was the simple

installation enabling the work to be accomplished by state crews.

Short span superstructures are almost exclusively "...slab or

beam-slab construction." Idaho reported 1 steel girder, 163

prestressed concrete, and 137 reinforced concrete short span bridges

3 built during the 10 year period (1964-1973). Oregon's Chief Bridge

Engineer reported 7 steel girder, 220 prestressed concrete, and 173

* reinforced concrete short span bridges built during the same time

frame (GangaRao and Taly, 1976). It was unclear from the available

I report documents if these numbers represent all bridges built in the

state or only those for which the state agency was responsible. It is

I

I 29

interesting to note that during a similar time frame Wallowa County,

Oregon constructed up to 150 prefabricated steel bridges with county

crews (Godfrey, 1975). Therefore it is believed that the information

from GangaRao and Taly's survey represents bridges constructed

only by state agencies. Washington state did not respond to the

survey, however; GangaRao and Taly noted that Washington used its

own standard prestressed concrete I and box sections for bridge

construction (GangaRao and Taly, 1976).

I A questionnaire was also utilized in the National Cooperative

Highway Research Program Report 222 "Bridges on Secondary

Highways and Local Roads Rehabilitation and Replacement". It was

sent to the 50 state highway agencies. In addition, site visits were

conducted to ten of the state transportation agencies including

I Washington Department of Transportation and one local

transportation agency, the Washington County Road Administration

Board. Information, predominantly from the state officials, indicated

* steel beam bridges were the most common type of secondary

highway bridge superstructure in the nation. Following steel beams

I in order of frequency were timber beams, concrete beams, concrete

slabs, steel trusses, prestressed concrete, concrete arch, and box

beams. The most common type of structure involved in bridge

failures were steel trusses followed by timber, steel beam,

prestressed concrete, stone arch, concrete beam, and "others". It is

* important to note that the two principle causes of failure were

believed to be overloading and collision rather than deterioration

I (NCHRP Report 222, 1980).

II

30

Hill and Shirole (1984) examined 3,692 bridge replacements in

IMinnesota from 1973 to 1983 for spans up to 100 feet. Of this total

1830 were constructed of concrete, 693 of steel , 564 of prestressed

Iconcrete, 841 were of timber and the remainder attributed to

I masonry, wrought iron, and aluminum. They found that in

Minnesota there appeared to be a trend away from cast-in-place

concrete. The reasons cited were the "... time consuming falsework,

formwork, cure, and field quality control for such construction during

Minnesota's limited construction season." Prestressed concrete

beams were found to be "...15 to 20 percent more economical..." than

steel beam superstructures. In addition with the shallow depths of

I double-T, bulb-T and quad-T precast sections, grading work for the

approaches was reduced which eliminated costly site work. One of

I the noted advantages of steel and timber bridges over concrete

structures was that these materials could be constructed year round

as opposed to concrete structures which required special

I considerations during the harsh Minnesota winters (Hill and Shirole,

1984).

I Sprinkel (1985) took the results of NCHRP Report 222 and

focused on six prefabricated systems believed to be most frequently

utilized. The six systems, all constructed of concrete, were: precast

I concrete slabs, precast box beams, prestressed I-beams, precast deck

panels, permanent bridge-deck forms, and parapet and rail systems.

I He developed a questionnaire that was sent to "most" of the bridge

engineers in the fifty states and the District of Columbia as well as

other major bridge agencies such as Alberta, Canada. Sprinkel found

I that the use of prefabricated elements has continually increased and

I 31

Iwas predicted to continue. Use of prefabricated elements increased

because of reduced first cost and accelerated construction. Sprinkel

found that first costs have far greater weight in bridge selection than

life cycle costs. However he noted that bridges on low volume roads

Ishould be designed to reduce first costs vice maintenance costs.

More money may be spent on initial construction than could ever be

I realized in reduced maintenance costs over the life of the bridge.

The inverse is true for high traffic density bridges (Sprinkel, 1985).

I The available literature revealed common characteristics

considered in bridge material selection. The Prestressed Concrete

Institute emphasized the following factors in its publication on

I selection criteria for short span bridges: "...wide use and acceptance,

low initial cost, minimum maintenance, fast easy construction,

minimum traffic interruption, simple design, minimum depth/span

ratio, assured plant quality, durability, and attractivene.s"

(Prestressed Concrete Institute, 1980).

j Report 222 of the National Cooperative Highway Research

Program, ("Brilges on Secondary Highways and Local Roads

Rehabilitation and Replacement", 1980) found the following factors

universally considered on almost all bridge designs: "... required

structural capacity, traffic volume, anticipated future use, labor

I required for replacement (in-house or contractor), and cost." In

addition the report cited other site specific factors with various

I degrees -'f importance: experience, available c, .tractors, budget

constraints, material availability, and environmental priorities

I (NCHRP Report 222, 1980).

II

32

A value engineering study conducted on the selection of low-

volume road bridges (GangaRao, Ward, and Howser; 1988)

concentrat,.d on spans of 30, 60, and 100 feet with an average dail

traffic volime of less than 200 vehicles per day. This study

identified seven criteria as the most important for bridge system

selection: "... initial material cost, ease of construction, maintenance,

durability, service life, availability of materials, and unit weight of

bridge system" (GangaRao, Ward, and Howser; 1988). Twenty eight

designs were analyzed and estimated for first and life cycle costs.

These costs were nJLed as a function of six factors: supply an.

demand for the bridges, familiarity of local contractors with the

design, long term performance, ease of erection, maintenance and

rehabilitation, infltionary -rends of materials used in bridge

components, and availability of materials in the local area (GangaRao,

Ward, and Howser; 1988).

All of these studies provided a good foundation for research

into short span bridge materials in the northwest. They provided

insight into what has been accomplished in this field for other

geographic locations.

IResearch Methodology

Many short span bridges are off the primary road system.

County public works authorities are primarily responsible for these

I bridges and were chosen as the primary source of information for

this research. Various methods were considered to collect the

required information. Phone interviews were considered impractical

considering the total number of counties (119) in Idaho, Oregon, and

Washington and the restricted time for the study. A survey was

considered the most efficient way to gather information on short

span bridges.

The maximum length of the survey was limited to three pages

with a total of 20 questions. A questionnaire of this length could

include all desired questions and could be answered by a

knowledgeable county engineer in 15 to 20 minutes. A longer

survey would have added limited additional information but would

have added additional response time. It was felt the additional time

would discourage more officials from responding.

The original questions were formulated into a trial survey. In

order to confirm that the research objectives would be met by the

questions and that all questions were clear and answerable this

survey was reviewed by two Snohomish County bridge engineers.

Both engineers were interviewed about the Snohomish County bridge

program and short span bridges in general. Then each question in

the trial survey was reviewed with them in detail. From these

interviews the trial survey was modified to form the final survey

I (Appendix A). The answers to question eight were modified as a

result of the trial survey. Cast-in-place and precast concrete were

I

I 34

Icombined into the single answer, concrete. This was done to simplify

3 the response. Most county engineers know what material an old

bridge is constructed of but do not necessarily know how it was

I constructed. For all other questions, cast-in-place and precast

3 concrete were considered separately. The literature revealed that

cast-in-place and precast have different levels of use because of the

_ different construction techniques. It served the purposes of this

research to consider them as separate materials.

IThe first six questions about staff size and work load, allocation

of funds, budget sources, code requirements, number of bridges, and

average daily bridge traffic (ADT) were developed to determine if

3 these factors influence material selection. Additionally this

information provided background information on each county and

I the emphasis which each county placed on bridge replacement.

It was desirable to determine what type of materials were

used in existing bridges and those proposed for future bridges.

* Questions eight and nine probed the number of deficient bridges and

the characteristics of those requiring replacement. Typically a

Idistinction is made between structurally deficient and functionally

obsolete bridges. To simplify the responses this was not done. It

was assumed that the number of structurally deficient and

functionally obsolete bridges was distributed in the nearly 1:1 ratio

as reported by the Secretary of Transportion in 1989.

-- The objectives of questions ten and twelve were to determine

present and future trends in material selection. Question ten focused

on future choices and question twelve focused on bridges constructed

35

in the previous three years. The impact that length of span has on

bridge material selection was another aspect of question twe!ve.

In the literature review, a number of citations emphasized the

advantage of erecting wood and steel bridges with "in house"

personnel. Question eleven was specifically written to determine

how recently completed county bridges were erected.

Costs were a primary focus in most of the literature on bridge

repair and replacement. Typically these costs included only those

related to the construction of a new bridge. Life cycle costs and user

costs were rarely considered in documented bridge costs. The

established standard in the literature expressed costs in units of

dollars per square foot of bridge deck. Typically these costs were

taken from the final price of a construction contract. In question

thirteen the average costs for bridges construrted from 1988

through 1990 were requested in units of dollars per square foot of

bridge deck.

Material availability can influence material selection. The

number and proximity of material suppliers in a region are

significant indicators of material availability in a county. This

information was requested in question fourteen.

U Respondents were requested in question 15 to weight the

utilization in bridge substructures, superstructures, and deckings of

cast-in-place concrete, precast concrete, steel, and wood. The scale

ranged from I (low utilization) through (10 high utilization). It was

surmized that a comparison of the average answers for each material

I -would provide information on the frequency of use of the four

primary bridge materials. Materials receiving higher averages would

I

UI 36

be considered the most desired and utilized materials for that bridge

* component.

Questions 16 through 19 individually focused on one of the

I subject materials. In each question the respondents were asked to

numerically rate one of the four materials on eleven factors. The

rating scale ranged from 1 (Disadvantage) through 5 (Advantage).

Averages would be determined for the each of the eleven factors for

the four materials. It was hypothesized that a comparison of the

averages for each factor in each question would provide information

on the perceived advantages and disadvantages of each material. A

comparison of the averages between the four materials for each

factor would provide the relative advantages and disadvantages of

each material.

The factors for questions 16 through 19 were: "simple design",

"familiarity in the department", "material cost", "material

availability", "initial construction cost", "contractors familiarity",

"speed of construction", "low maintenance", "durability", "funding

availability", and "aesthetics". Ten of the factors were those

addressed in prior research and emphasized in the literature. An

additional factor, "funding availability", was stressed as being

important by the Snohomish county bridge engineers and was

included as the eleventh factor. A twelfth answer "others" was

included for unanticipated factors.

An explanation is provided to clarify the significance of each

factor. The design of a structure varies depending on what material

is chosen. The first factor, "simple design", questioned if the design

process had any influence on material selection. Some materials are

1 37

Ueasier to utilize in bridge design because of simpler connections,

more uniform material responses, and more consistent quality of

materials.

- Often times a material is chosen because it is familiar to the

county officials and to contractors that construct bridges. Yet this

may not be the best material if all factors are considered. It is

possible materials with superior characteristics are not considered

because they are not familiar and are not utilized regularly. The

i queston about "familiarity in the department" and "contractors

* familiarity" were included to determine which materials were most

familiar to the owner and the contractors.

* The cost of a bridge is reflected both by the initial costs and

other costs extended over the service life of a bridge. How material

i• selection affects the cost of installation of a bridge is reflected by"material cost" and "initial construction costs". It can be assumed,

with all other factors being equal, the least costly combination will be

the most popular. It was assumed that respondents would consider

"in place" material costs including transportation and placement.

3 Indirectly "speed of construction" can also have immediate cost

effects although they are not as obvious. Normally, reduced

construction time equates to reduced construction costs. In addition

* faster bridge construction means reduced bridge closer time which

reduces user costs. "Low maintenance" and "durability" are

important factors effecting the economics of a bridge. Materials that

require little maintenance and have high durability will typically be

I more cost effective for the entire life cycle of a bridge.

i

I 38

"Material availability" is effected by fabrication time, shipping

distance, and the number of suppliers within close proximity to the

county. Materials that are not available cannot be utilized. Those

I that are procured from a great distance require transportation costs

that typically raise costs and make them less competitive. Long

fabrication time may make a material less attractive, particularly if a

bridge is "out" and must be replaced expeditiously. A limited

number of available suppliers may result in a backlog of orders,

reduced competition and increased cost of the material.

There are a number of sources of funding available to local

authorities other than county revenues. These funding sources may

have requirements that influence a number of aspects of a bridge

project including material selection. If a county official desires to use

state or federal funding the requirements of the funding source must

be fullfilled. For example the Highway Bridge Replacement and

Rehabilitation Program (HBRRP) requires that bridges funded under

this program must meet HBRRP standards and regulations and when

completed must no longer have any deficiencies. Since the HBRRP

I follows the AASHTO criteria for bridge design any county receiving

funding under the HBRRP program must comply with the AASHTO

criteria. It is also possible that state statutes stipulate that state

* funding be provided under the condition that bridge materials be

manufactured in state.MILEMARKER

* The objective of question 20 was to determine the relative

importance various factors had in material selection for bridge

substructures and superstructures. This question was formulated so

*respondents would weigh the importance of each of these factors

I

39

independently on a scale of 1 (least important) to 10 (most

important). The average of the answers for each factor would be

indicative of the more critical factors. Factors with higher averages

can be considered more important for superstructure or substructure

material selection. The factors were similar to those in questions 16

through 19 except for deleting "familiarity in the department" and"contractors familiarity" and including "total life cycle costs" and"environmental impact". This was done to explore the emphasis

I material selection has on total life cycle costs and the environment of

- the bridge site.

"Total life cycle" costs takes into consideration all costs of a

bridge over the required service period. This includes initial

construction costs, maintenance costs, repair costs, and replacement

costs if multiple structures are required for the service period.

During the interview of the Snohomish county engineers it was

noted that environmental concerns were having an increasing impact

on bridge designs and material selection. This was believed to be

particularly true for the substructures. Materials that are not

capable of long clearspans require intermediate bents that reduce

the hydraulic opening. Environmental concerns focus on pile driving

- that disrupts the flow of water. Additional concerns include the

possibility that substructure materials may leach chemicals due to

constant direct contact with fresh water supplies.

After completion of the final twenty questions the survey along

with a cover letter were copied in sufficient quantity to mail to the

I target sample population. County officials in Idaho, Oregon, and

* Washington were chosen because they were a manageable sample

I 40

Ithat would be representative of trends in the northwest. Most

- previous studies on short span bridges surveyed state highway

officials and did not explore county bridge programs. The

I] differences between county and state operating budgets, bridge

average daily traffic volume, staff, and maintenance organizations

may effect material selection. The counties were considered a more

n representative sample because the majority of short span bridges are

under the jurisdiction of county officials.

-- Addresses for the counties were received from the Idaho

Association of Counties, Association of Oregon Counties, and the

Washington Association of County Officials. The survey was mailed

to a total of 119 counties in the states of Idaho, Oregon, and

Washington comprised of 44 county clerks in Idaho, 36 public works

I officials in Oregon, and 39 public works officials in Washington.

From the returned surveys, the raw data was entered on a

spreadsheet to facilitate the analysis (Appendix B). In addition the

data for questions 1 throughl0 and 15 through 20 were analyzed

with the use of the microcomputer version of the Statistical Package

U for the Social Sciences (SPSS/PC+) software (see Appendix C). This

enabled analysis of the frequencies of answers to individual

questions. The low responses to questions 11 thru 14 did not justify

. the use of the SPSS/PC+ program for analysis of these questions.

Results

Out of the 119 surveys sent, 50 were returned for an overall

response rate of (42 %). The breakdowns by state are: 27 responses

(69 %) from Washington, 16 responses (43 %) from Oregon, and 7

responses (16 %) from Idaho, (Appendix D). The high response from

Washington counties may be attributed to a closer identification with

the university conducting the survey. Typically for surveys, higher

responses are anticipated when the survey is addressed to an

individual. For the counties in Oregon and Washington the surveys

were addressed to a specific individuals who was either the county

engineer, public works director, road master, or bridge engineer. The

surveys were addressed to the "county clerks" for the counties of

Idaho since the names of public works directors were not available.

This resulted in the lowest response from the counties in Idaho.

Of the 50 returned surveys two were blank ( one from

Washington and one from Idaho) because neither county was

responsible for any bridges. This resulted in a total of 48 completed

surveys with usefull information. However the total responses

varied for each question because some of the 48 respondents did not

answer all of the questions. Those questions for which information

was not provided were reflected in the raw data as blanks (see

Appendix B) and in the SPSS input as a 9 or 99 (see Appendix C).

Questions I through 10 typically had 46 to 48 useable answers.

Questions 11,13, and 14 were answered by approximately half of the

respondents. Question 12 had 43 useable answers. The questions

that rated material utilization and factors in material selection

(questions 15-20) had between 38 and 40 useable answers.

42

The majority of the counties 41 (82%) did not have a full time

bridge engineering staff. Seven counties had a staff that typically

consisted of a single engineer whose time was split between bridges

and other responsibilities. These seven counties either contained or

were in close proximity to a large population center. One of the

larger Washington counties, large in terms of number of bridges,

budget, and traffic density, had three full time bridge engineers.

However that county was the exception when compared to the other

county responses.

The majority of the counties (77%) spent between l and 75

thousand dollars on bridge repairs. One county had a repair budget

of 1.5 million dollars. Almost half (49%) of the counties spent f.:jm

30 to 200 thousand dollars on bridge replacement. The replacement

budgets of the other counties ranged in 50 to 100 thousand dollar

increments, from 250 thousand dollars up to the largest replacement

budget of 2.0 million dollars. Eight of the respondents did not have

any money budgeted for replacement.

The majority of the money available for bridge replacement

came from the federal government (Table 1). More than half of the

respondents (24 out of 43) received 75 to 80 % of bridge project

funds from the federal government. Thirty five (81%) of the

respondents received some amount of federal funding. In most

cases the next largest portion of a bridge project was contributed by

the county responsible for the project. Counties have provided

between 10 and 100 % of the funds of bridge projects. However;

67% of the respondents have provided no more than 25% of the costs

of a project. Washington, Oregon, and Idaho provided varying

I 43

IIIII

TABLE 1. Number of Counties that Receive Federal. State.and Local Funding for Bridge Replacement

Percentage of Federal State CountyFunding:

0% 8 (18%) 26 (61%) 2 (5%)

1-19% 2 (5%) 10 (23%) 8 (18%)

20% 2 (5%) 1 (2%) 14 (32%)

21-79% 12 (28%) 4 (10%) 14 (32%)

80% 19 (44%) 1 (2%) 0 (0%)

81-100% 0 (0%) _1 (2%) 5 (13%)

Totals 43 43 43

I 44

degrees of financial support. Washington state provided relatively

little funding for bridge replacement. The majority of the

Washington respondents indicated a typical funding apportionment

Iof 20% County and 80% Federal. Oregon counties also reported only a

I nominal amount of state funding. The counties in Idaho recorded the

highest amounts and frequency of state support.

I Fifteen years ago short span bridges were not constructed to

any national standard (GangaRao and Taly, 1976). Today, the

AASHTO bridge specifications are the most common standard.

According to this survey 24 respondents (54%) utilized AASHTO

codes and an additional 9 (20%) used the AASHTO codes in

I conjunction with state requirements. Of the remainder, 10 utilized

state codes and one indicated it followed FHWA requirements.

i The counties were responsible for a total of 4584 bridges. The

number of bridges in each county jurisdiction varied from zero to

350. The majority of the counties were responsible for less than 100

bridges. As expected, the majority of the bridges had low average

daily traffic (ADT). The breakdown of the number of bridges by

traffic volume is as follows:

*2928 low volume bridges (less than 400 ADT) (70%)

*1000 bridges with ADT between 400 and 2000 (24%)

*233 bridges with ADT greater than 2000 ( 6%)

Most counties (42) had at least one low volume bridge. Only 25

of the counties reported having at least one bridge with traffic

volume over 2000 ADT. Almost half (112) of the bridges with ADT

I greater than 2000 were in four counties that contained or were near

3 a large population centers.

I

46

TABLE 2. Number (and percentage) of Deficient Bridges by State

Material Washington Oregon Idaho Totals

Concrete 136 (31%) 18 ( 8%) 33 (37%) 187 (24%)

Steel 118 (27%) 29 (12%) 26 (29%) 173 (23%)

Wood 188 (42%) 184 (80%) 30 (34%) 402 (53%)

Totals 442 231 89 762

Note that information regarding the number of existing bridges of

each type of material was not obtained in the suivey.

47

III

TABLE 3. Number and Percentage of Bridges Constructed orUnder Construction (1988-1990 )by Length

Material Less than 30 to 60 ft. 61-120 ft. TotalsI 30 ft.

Precast 9 (38%) 23 (53%) 45 (83%) 77 (64%)

Cast in F.ace 2 ( F%) 6 (14%) 6 (11%) 14 (11%)

Steel 0 (0%) 12 (28%) 2 (4%) 14 (11%)

Wood 13 (54%) 2 (5%) . ._ (2%) 16 (14%)

Totals 24 (20%) 43 (35%) 54 (45%) 12iIIIIIIII

1 48

indicated that precast concrete beams were used on six 160 foot

spans..

Precast concrete will continue to be the dominate short span

-- bridge material. Four out of five new short span bridges will be

* constructed of precast concrete (Table 4). Only a few counties in

Washington state will use steel or wood for future bridges. Counties

I in Oregon indicate the number of steel and wooden bridges

constructed will small compared to concrete structures. The counties

_ in Idaho seem more flexible in the choice of bridge material.

Question eleven proved to be ambiguous, since there are two

possible ways of interpreting the question. The question was

intended to request the percentage of all new bridges constructed by

contract or county crews. For example the responses from one

county in Washington indicate 80% of ali new bridges were precast

concrete constructed by contractors, 5% were steel constructed by

contractors, 10% were precast concrete constructed by county crews,

- and 5% were wooden bridges constructed by county crews (see

Appendix B). This interpretation of the question reveals the most

*- information about the proposed materials and methods of bridge

replacement. However the majority of the counties interpreted the

requested percentage to be for each material. As an example one

county indicated that 100% of the cast-in-place, 100% of the precast

concrete, 100% of the steel, and 75% of the wooden bridges will be

constructed by contractors and 25% of the wooden bridges will be

constructed by county crews (see Appendix B). In either case a

I- review of the answers indicated the majority of new bridges

n typically will be contractor built precast concrete structures. The

I

49

I

I

H TABLE 4. Principle Construction Materials for New Bridges

i Material Washington Oregon Idaho Totals

U Precast 315 (90%) 152 (81%) 27 (36%) 494 (80%)

Cast in Place 21 (6%) 3 (1%) 26 (36%) 50 ( 8%)

U Steel 3 (1%) 16 (9%) 15 (20%) 34 (6%)

Wood 11 3%) 16 (9%) 7 (8%) 34 (6%)

Totals 350 (57%) 187 (31%) 75 (12%) 612

I

III

I

- 50

counties that do utilize "in house" personnel typically will construct

wooden bridges. A small number of precast bridges may be

constructed by county personnel.

I Most of the cost information was for precast concrete bridges

indicating that it was the most common bridge material (see

Appendix E). Bridge project costs varied a great deal due to the

effect of site conditions. A comparison of material costs within

counties indicated that wood was the least expensive bridge material

I followed by precast concrete. Averages for each material are

* presented in Table 5. The averages are deceptive because they are

based on relatively few responses and a small number of bridges.

* However individual county costs can be compared to the average

costs to determine if the bridge costs for that county are

i comparitively high. Only half of the respondents provided

information on bridge material suppliers. Comments made by the

respondents indicated that the degree of confidence

* confidence in the answers decreased as the distance in the question

increased. Respondents either knew the number of suppliers in the

local area (< 10 miles) or made educated estimates. However, as the

distance increased up to 200 miles, respondents had less information

I and made less accurate estimates (Table 6). Most of the county

bridges are replaced by contractors and it can be assumed that

county officials do not procure the bridge materials. Rather,

contractors are responsible for procurement of the spccified material

under the conditions of the construction contract.

To determine the future use of cast-in-place concrete, precast

concrete, steel, and wood in substructures, superstructures, and

II 51

Table 5. Average Costs in Dollars per Square foot of bridge deck.

UB _Cast-in-Place Concrete1988 1989 1990$70.00 (4 responses) $65.60 (5 responses) $112.5 (2 responses)

_ _ _ Precast Concrete1988 1989 1990$60.24 (15 $92.87 (15 $91.71 (10responses) responses) responses)

___Steel

1988 1989 1990$90.33 (3 responses) $89.00 (4 responses) $72.50 (2 responses)

_ _ _ Wood1988 1989 1990

$30.00 (4 responses) I$62.20 (5 responses) $49.00 (4 responses)IIIIII

U 52

IIII

I TABLE 6. Estimated Number of Material Suppliers

Material Less than 10 mi 10 to 100 mi, 100-200 mi..

I Precast 2 38 38

Cast in Place 28 57 26

Steel 3 23 21

Wood 9 35 27IIIIIIIII

53

decking county officials were requested to rate the subject materials

on a scale from 1 (low utilization) to 10 (high utilization). The most

highly utilized material in the substructure will be cast-in-place

concrete (Figure 3). Precast concrete will be the most utilized

material in the superstructure (Figure 4), and decking (Figure 5).

Steel will rarely be used for decking and only five respondents

* indicated it will have limited future application in substructures and

superstructures (Figures 3, 4, and 5). Wood will rarely be utilized in

the substructure and only four respondents indicated that it would

be utilized in the superstructure (Figures 3 and 4). Similarly only

four respondents indicated that wood will be utilized for bridge

* decks (Figure 5).

The advantages and disadvantages of cast-in-place concrete,

precast concrete, steel, and engineered wood were rated on a scale

from 1 (disadvantage) to 5 (advantage). The responses are

presented as; bar graphs in Figures 6 through 16. Average responses

for each factor are shown on the bar graphs under the material keys.

Examination of these bar graphs reveals the relative advantages and

disadvantages of each material. It is apparent that precast concrete,

with the highest average answers for nine out of eleven "actors (see

Table 7), dominates all the other materials. Only cast-in-place

* concrete is considered a more available material and wood a more

aesthetically pleasing bridge material.

* Both low maintenance and durability are important factors for

the selection of both substructure and superstructure materials.

I Precast and cast-in-place concrete exhibit lower maintenance and

I

I= 54

I N 3U 30M 27

* BE 24R 21

o 18f

15R12"ES 9P

I 06

N 3SE 01 .. I=XMALS34 7-'8 9-10

RESPONSES (10 -High Utilization)O Wood OSteel F3Cast in Place OPrecast

Average Values: 2.29 3.66 8.53 3.31

Uz n Figure 3.Utilization of Materials in the Substructure

INN 30

M 27BE 24

21

o 18f

15

R 12E -

SPI 0N 3SE-- S O 'J

0-2 3-4 5'6 7-8 9-'10

RESPONSES (10 -High Utilization)I OWood GSteel 0 Cast in Place OPrecast

Average Values: 2.96 3.17 5.61 8.58

I IFigure 4.Utilization of Materials in the Superstructure

* 55

UUM 27BE 24R 21

o 18

0 15R 12 .E

* S9P

6N3

* SE0S

I RESPONSES (10= High Utilization)OWood OSteeI [SCast in Place ElPrecast

Average Values: 3.32 2.86 6.59 7.72FiF .a 5.l

*Utilization of Materials in the Bridge Deck

i 56

III

TABLE 7. Averages for the Prioritized MaterialSelection Factors

Priority Material Engineered 51&d Cast-Steleal PrecastSelection Wood Concrete ConcreteFactors

I I Low 2.1 2.27 4.09 4.37

Maintenance

2 Durability 2.07 3.12 4.22 4.28

3 Construction 3.49 2.66 2.91 3.53Costs

4 Material Cost 3.41 2.61 3.27 3.63

i 5 Material 3.51 2.98 4.13 3.67Availability

6 Speed of 3.59 3.22 2.41 4.57Construction

7 Simple Design 3.54 2.95 3.41 4.09

8 Familiarity in 2.9 2.54 3.42 3.79Dpt.

9 Contractor 2.88 2.78 3.77 3.87Familiarity

10 Funding 2.88 3.05 3.42 3.55Availability

i 11 Aesthetics 3.59 3.02 3.3 3.53

Scale for Answers 1= Disadvantage, 3=Neutral, 5= Advantage

III

II 57

have higher durability in comparison to wood or steel (Table 7,

Figures 6 and 7). These factors have a substantial influence on the

engineering economics of a structure. As mentioned previously the

I importance of these factors is magnified since counties typically fund

* all maintenance costs.

The differences in the maintenance and durability of concete,

steel, and engineered wood can be attributed to material properties.

Corrosion diminishes the durability of steel necessitating painting. A

I number of counties commented in the survey that the painting

* requirement of steel increased maintenance costs which eliminated it

as a bridge material. Although treated wood does not require

painting, maintenance costs for wooden bridge in general were still

considered too costly by the respondents. Comments in the survey

I indicated that more frequent inspections were necessary with

wooden bridges to insure that all connections remained tight. It was

felt that engineered wood was subject to deterioration and was not

considered as durable a material as concrete or steel. County officials

stated it was "...difficult to detect deterioration" in a wooden

structure. One official preferred to use wood more often but did not

because of the lingering concerns about longevity. Another official

- commented that the "...costs were high relative to life" and that

wooden bridges were not much cheaper than concrete. The

difference in maintenance and durability between precast concrete

and cast-in-place concrete is explained by the differences in the final

quality of the material. The controlled environment of a precast

yard usually results in a higher quality product than can be

*. produced with concrete placed under field conditions.

IN 3058M 27B2TE 24R 21

0 18f

R 12

S

EN 0 *..

RESPONSE VALUES (5- Low Maintenance)I0Engineered Wood 0 Steel ~Cast-in-Place *PrecastAverage Values: 2.10 2.27 4.09 4.37

-Cmaio Figure 6.Compaisonof RequiredManenc

N N0U 3M 27BR 24

0 18

R 12E

N 3

SI123 4 5RESPONSE VALUES (5= High Durability)

E3 Engineered Wood MSteeI K3Cast-in-Place 0PrecastAverage Values: 2.07 3.12 4.22 4.28

Comparison of Material Drblt

59

The next most important factor was construction costs (Table 7 and

Figure 8). Here there is a marked difference between precast and

cast-in-place concrete. The higher average for precast concrete

indicates that the prefabrication of bridge components greatly

reduces construction costs. One county noted that the trend has been

away from cast-in-place concrete because of the time required for

formwork, the fact that falsework can interfere with stream flows,

and the poor quality of the finished concrete.

Material cost is one of the major components of construction

costs. Some respondents may have considered these factors too

closely enmeshed to be able to distinguish them individually. This is

most evident by noting the neglible difference in the average

answers for "construction costs" and "material cost" for steel in Table

7 and Figures 9 and 10. Steel has high construction costs which is

partly due to low material availability and high material cost.

Conversely precast concrete and engineered wood had the lowest

construction costs and were the least expensive materials.

Cast-in-place concrete appears to be a more expensive material than

* precast concrete and engineered wood even though it is considered

the most available material (see Table 7 and Figures 9 and 10). It

appears that respondents typically consider "in place" material costs

I such as placement and finishing for cast-in-place concrete which

includes labor costs. This would make cast-in-place concrete a more

I expensive material.

Speed of construction can be expected to have a direct

I relationship with the cost of construction and the availability of

material. Materials that can be constructed in a shorter period of

N 3060U 3M 27B IE 24R 21

0 18f

15R 12ES 9P

06N 3

E ME....0S

4 235RESPONSE VALUES (5=Low Costs)

0Engineered Wood ~Steel gCast-in-Place 0 Precast

Average Values: 3.49 2.66 2.91 3.53

Compriso ofConstruction Css

*N 30UM 27B

R 21

0 18f

15R 12E

0 6 nN S

* 1 2 345

RESPONSE VALUES (5=Low Material Costs)

E0 Engineered Wood ~Steel ICast-in-Place 03 Precast

Awerage Values: 3.41 2.61 3.27 3.63

Figure 9.Comparison of Material Costs

61

time can have lower construction costs. Projects will be completed in

a shorter period of time if material is readily available. Precast

concrete and engineered woxd both are readily available and have

relatively lower construction costs (Figures 8 and 10). As predicted

they also have the shortest construction times (Table 7 and Figure

11). Conversely cast-in-place concrete appears to have the longest

construction time. This is not due to long lead time in procurement

or material characteristics, rather it is due to construction methods.

A great deal of time is required to build the forms; install the

re'iforcing steel; place, finish, and cure the concrete; and finally strip

the forms.

The design of a structure and l'ow familiar the material was to

county o.-icials and contractors did not have the same economic

emphasis as the previous six factors and therefore was not as critical

in material selection. County officials felt concrete design was

familiar both in the department and to contractors who bid upon

county contracts (Table 7, Figures 12, 13, and 14). Steel designs

appear to be more complex. Steel is not as familiar to county

engineers and contractors as concrete (Table 7, Figures 12, 13, and

14). It appears that with the increased utilization of precast concrete

I county officials have not considered short span steel bridges and

have become unfamiliar with the material.

Replacement of county bridges are funded to a large degree

from sources outside county revenues. The federal government is

the primary source of funding. Funding is readily available for

I concrete bridges and to a lesser extent for steel structures. It

appears that more respondents felt that less funding was available

III I IIII

I 62NU 30

M 27BE 24R 21_

o 18

i 15

R 12E

*S 9P

o 6N 3

ES 2 3 45

RESPONSE VALUES (5=High Availability)

0 Engineered Wood MSteel 0 Cast-in-Place E3 PrecastAverage Values: 3.51 2.98 4.13 3.67

U Figure 10i IComparison of Material Availability

I NN 30U

M 27BE 24

RIR 21

o 18

15

R 12ESP0N 3SE0

2 3 45

RESPONSE VALUES (5= Fast Construction)

0 Engineered Wood M Steel O Cast-in-Place 0 PrecastAverage Values: 3.59 3.22 2.41 4.57

Figure 11.Comparison of Speed of Construction

II

63NN 30M 27BE 24R 2 1 _

o 18f

15R 12

ES .

06N 3S .

E 0M1 2 3 5

RESPONSE VALUES (5=Simple Designs)

0 Engineered Wood 0 Steel MCast-in-Place 0 PrecastAverage Values: 3,54 2.95 3.41 4.09

Figure 12.Comparison of Design Complexity

! NU 30U-

M 27BE 24R 21

o 18f

15

R 12ES 9N,Po 6N 3SE 0 .S f ; 3 45

RESPONSE VALUES (5=Familiar Material)

03 Engineered Wood C3 Steel Ed Cast-in-Place 0 PrecastAverage Values- 2.9 2.54 3.42 3.79

'i Figure 13.Familiarity of the Materials in the Departments

II

65N 30UM 27-BE 24_R 21_

o 18f* 15R 12P..E

P6

N 3

S

1 2 3 4 5RESPONSE VALUES (5= Familiar Material)

03 Engineered Wood DSteeI 0 Cast-in-Place 0l P recastAverage Values: 2.88 2.78 3.77 3.87

Famliaityof Figure 14.FamliaityofContractors with the Materials

N 30M 27-BE 24_

0 18

15R 12E

6IN 3 ....

E 1 3 ..SJ 4 5-

RESPONSE VALUES (5= Funding Available)QEngineered Wood OSteel ~Cast-in Place DOPrecast

Average Values; 2.88 3.05 3.42 3.55

H ComprisonFigure 15.ICompaisonof the Availability of Funding

0 N8

R B2E 2R 21

N 13

SI E 0FT1 2 345

RESPONSES VALUES(5=Aesthetir. Appeal)

03 Engineered Wood USteeI 63Cast-in-Place 0 PrecastAverage Values: 3.59 3.02 3.30 3.53

* Figure 16.Relative Aesthetic Value of the Materials

I 66

Table 8. Average Responses for Substructure andSuperstructure

Material Selection Factors (l=least important, 1O=most important)

FACTOR IMPORTANCE in IMPORTANCE inI SUBSTRUCIUIRE SUPERSTLJCTUREMATERIAL MATERIALSELECTION SELECTION

Maintenance Costs 8.43 8.57Durability 8.44 8.26IConstruction Costs 8.08 8.07Total Life Cycle Costs 7.95 8.07Material Costs 7.58 7.45

Material Availability 7.24 7.28Speed of Construction 6.80 7.07Familiarity of Design 6.18 6.32Funding 6.18 6.00RequirementsIEnvironmental 5.74 5.49ImpactAesthetics 4.30 4.55

II

III

67

as the number of material suppliers, was not as readily available and

were not answered with the same frequency or degree of confidence.

However all the responses proved valuable in determining which

materials are being utilized in short span bridges and what factors

influence material selection.

I

Summary

Rarely does a county public works director assign an

engineering staff full time to the county bridge program. Time

constraints and other responsibilities may limit county engineers

from exploring multiple bridge replacement options, choosing instead

an expedient "standard design" commonly utilized in the county.

_- Federal funding of county bridge projects was anticipated since

the HBRRP authorizes the FHWA to fund up to 80 % of projects on the

- national bridge inventory. This may result in many counties

deferring bridge work until federal funds become available,

allocating limited county resources to other equally or less pressing

requirements. In Washington, Oregon, and Idaho; state funding

typically is not allocated to bridges off the Federal-aid system.

I County officials are responsible for funding the maintenance of

the bridges under county jurisdiction. Limited maintenance budgets

I influence county bridge designs and material selection. County

* engineers are encouraged to choose materials that require low

maintenance despite high initial costs because the federal

government will fund up to 80% of a bridge project. These low

maintenance costs reduce the total annual county maintenance

expenditures. In some locations bridge materials with high initial

costs and low maintenance requirements may not be the most

economical in terms of overall life cycle costs. However, such

materials are attractive to county officials because a larger portion of

the total life cycle costs are funded by the federal government "up

I front" thereby reducing county expenditures.

II

n 69

U There are twice as many existing wooden bridges requiring

replacement than either concrete or steel. This may be due to the

total number of existing wooden bridges being greater than the total

I number of existing concrete or steel bridges. It is also possible that

the majority of existing wooden bridges are older than existing

concrete and steel bridges. Wooden bridges may not be as durable

3 for the majority of site conditions encountered. Most respondents

indicated that wood is not as durable as steel, cast-in-place concrete,

* or precast concrete and has the highest maintenance costs of all three

materials. Inadequate maintenance would have the most significant

impact on wooden bridges resulting in deterioration and earlier

replacement. Limited county budgets may have restricted the

minimum levels of required maintenance.

Most bridge costs are established from the final price of

construction contracts. However each bridge site is unique with

many variables that effect design and make it difficult at best to

compare costs between materials. Bridge costs are influenced by:

site conditions, time of construction, design, material costs, and

competition. Material cost is only one of many factors that

determine the overall cost of a bridge project. The costs provided by

the county officials (see Appendix E) reflect this variability. The true

indication of the economics of the different materials can only be

determined by considering each bridge site individually and

performing an economic analysis on each site fui each material.

Bridge selection is significantly influenced by economics This

is readily apparent from the priority and weight given to factors in

Table 7. County officials gave greater emphasis to long term

70

expenditures such as maintenance and durability rather than short

term expenditures such as construction or material costs.

Upon completion, a bridge funded under the Highway Bridge

Replacement and Rehabilitation Program (HBRRP) must comply with

all HBRRP standards and regulations and be free of deficiencies.

Unlike concrete and steel wooden guard rails do not meet the criteria

of the HBRRP. The HBRRP follows the AASHTO codes as do the

majority of counties. Wooden guard rails do not meet the crash test

criteria of AASHTO and therefore do not meet the requirements of

the HBRRP. Since federal funding under the HBRRP is not available

for wooden bridges they will not often be considered.

- Conclusions

Concrete is the material of choice for most short span bridges.

Durability and low maintenance are the two key factors delineating

its superiority over steel and wood. Most substructures are

cast-in-place concrete while superstructures show a high utilization

of precast elements. For decking there is a slightly higher preference

for precast deck panels. In the future, four out of five new

superstructures will be built of precast concrete elements. The large

majority of bridges will be built by contractors and not county crews.

Precast concrete was considered the material with the greatest

number of advantages for utilization in short span bridge

superstructures and decking. Superior quality control of the finished

concrete along with faster construction has contributed to its

dominance over cast-in-place concrete. In forty years it has become

the dominant material for short span bridge construction and will

I show increasing use in the future.

* Cast-in-place concrete was the material with the second

greatest number of advantages. The noted disadvantages of

cast-in-place concrete are related to construction. Construction is

slower and construction costs are considerbly higher than precast

concrete for superstructures and bridge decking. However it is

easier and more cost effective to form and place concrete

substructures than it is to assemble precast elements. Cast-in-place

concrete does not require heavy lifting equipment which reduces the

placing cost in comparison to precast elements. This accounts for the

predominant use of cast-in-place concrete for bridge abutments,

footings, and retaining walls.

I73

Engineered wooden bridges have many positive factors that

warrant consideration. Wooden bridges have simple designs, low

construction costs, and can be constructed in a relatively short time.

I The initial costs for engineered wood superstructures may be

*economically competitive with precast concrete elements and more

economical than cast-in-place concrete or steel superstructures. A

number of counties use wood for superstructures and decking in low

volume spans under 30 ft. There is a potential for greater utilization

of engineered wood bridges considering the majority of low volume

bridges that exist and the fact that approximately one third of the

county bridges requiring replacement are under 30 ft.

Despite these observations, wood will rarely be utilized in

substructures and superstructures. Other factors outweigh the low

initial cost for wooden bridges. The maintenance required on

wooden bridges and their poor durability discourages greater

utilization. Although wooden bridges can be assembled with

semi-skilled labor, such as county crews, the majority of county

bridges are built by contract instead of by county personnel.

Wood preservers claim that wooden bridges can be expected to

last 50 years with contemporary preservation methods. However

the general consensus of county officials is that wooden bridges are

still subject to decay. This conception needs to be dispelled before

wooden bridges will be considered a viable choice for short span

bridges.

Steel is generally not considered by county officials for

substructures or superstructures of short span bridges, due to high

initial costs as well as painting requirements. The initial cost of

74

construction and long term expenditures are higher than concrete.

The small number of counties that do utilize steel structures consider

them only for spans between 30 and 60 feet.

Twenty two years after the Silver Bridge collapse in West

Virginia, county officials in the Northwest are very sensitive to the

importance and cost of bridge maintenance. Low maintenance and

* high durability are the two principle factors that influence the

selection of bridge materials. Materials that have these

* characteristics such as precast concrete and cast-in-place concrete

are typically chosen by county officials, even for bridges with low

traffic volumes. However, in isolated areas wooden or steel bridges

are still preferred over precast or cast-in-place structures because of

low initial costs and ease of erection. These counties are aware, as

recommended by Sprinkel, (1985) , that it is more economical to

reduce first costs rather than long term maintenance costs for low

volume bridges. The higher initial cost of a more durable and easier

to maintain bridge may never be recovered in the service life of the

structure.

Maintenance costs are funded completely by the counties,

however; the federal government will pay, through the Highway

Bridge Replacement and Rehabilitation Program, up to 80% of the

cost of a new bridge or rehabilitation of an old bridge. This funding

structure influences county officials to choose materials that have

low maintenance cost even if the initial costs are higher in

comparison to other materials. The federal government will pay a

large portion of the "up front" costs and county expenditures on

maintenance will be reduced over the life of the bridge. More of the

75

- total life cycle costs of the structure are paid "up front" by the

*federal government in lieu of over the life of the bridge by the

county.

The bridge infrastructure in Idaho, Oregon, and,Washington

_ still requires extensive rehabilitation and replacement. However

federal programs are in place that provide funding for county bridge

projects both on and off the Federal aid system. The HBRRP will

assist counties in funding bridge rehabilitation and replacement but

I additional funding is necessary if all existing ano future deficient

bridges are to be corrected.

Recommendations

Funding sources for bridge rehabilitation and replacement will

become exceeaingly limited with legislated reductions in the federal

budget. County officials may be forced to make bridge selections

that have lower initial costs. Shifting economic conditions may ha,'e

I a marked influence on the initial cost of materials. In particular,

rising energy costs will impact the cost of construction materials in

varying degrees. County officials should be aware of the ripple effect

that rising energy costs have on total life cycle costs for precast

concrete, cast-in-place concrete, steel, and wooden bridges. Economic

I analyses should be performed with designs of concrete, steel, and

wood to determine if reduced expenditures on maintenance justify

higher initial construction costs.

* Concrete clearly has many advantages over steel and wood for

short span bridges; however, it is still the material with the heaviest

dead load. Bridges that utilize existing substructures typically are

more economical. Due to the heavier dead load, concrete may not be

I

76

used on substructL :es which were constructed for steel or wooden

superstructures. County officials may need to work closely with

concrete producers to determine if a economical lightweight concrete

is available to utilize existing substructures.

Couity officials receive a large portion of rehabilitation and

replacement funding under the HBRRP. Bridges funded under this

Iprogram must comply with AASHTO criteria. Since wooden guard

rails have not been crash tested in accordance with the AASHTO

criteria they are not eligible for federal funding. Wooden bridge

fabricators should have a standard rail design tested and accepted in

accordance with the AASHTO criteria. Thi,; w-'uld make it possible

Ifor counties to seek funding for wooden bridges under the HBRRP.

Steel maintenance and fabrication costs must be reduced if

steel is to become a practical short span material. Steel producers

should concentrate on developing a true weathering steel for the

climates encountered in the Pacific Noithwest. This would eliminate

the painting requirement and would make steel a more economical

choice for the county engineers.

Further Research

Twice as many wooden bridges require replacement as

concrete or steel bridges. This wzuid appcar to validate the

consenisus of county officials who do nct believe wood is a durable

bridge material. Further investigation is warranted to determine the

I-eason more wooden bridges are in need of replacement than steel or

concrete

ICounty officials felt that steel and woou, n bridges were not as

economical as concrete bridge,. However few if any counties actually

I

I77

U keep records of complete life cycle costs. It would be beneficial to

conduct further research into life cycle costs. Case studies could be

performed on wooden steel and concrete bridges under similar

I conditions. All costs associated with these bridges could be

reconstructed to determine estimated life cycle costs. This would

provide further insight into which materials are the most economical.

IIII

IIIII

I

II

I

IReferences

Elsasser, H.B.,"Current Practices in Steel Construction", HRB SpecialReport 132. Systems Building for Bridges, Highway Research Board,National Research Council, Washingtion D.C., (1972) pp. 31, 32

I Erikson, Mervin 0., "Engineered Timber Systems for Short SpanBridges",(1989)

Godfrey, K.A., Jr., "Cutting Cost of Short Span Bridges", CivilEngineering ,(July 1975) pp. 42-46.

Hale, Charles C., "Static Load Test of Weyerhaeuser Bridge RailSystem", Weyerhaeuser Company Research and Development, April1977.

Heins, C.P. and Firmage, D.A., Design of Modern Steel Highway

Bridges, John Wiley and Sons, (1979)

Heins, C.P. and Lawrie, R.A., Design of Modern Concrete HighwayCBridges, John Wiley and Sons, (1984)

Hill, J.J., and Shirole, A.M., "Economic and Performance considerationsfor short-span bridge replacement structures", TransportationResearch Record 950, (1984), pp 33-38.

Kosmatka, Steven H., and Panarese, William C., Design and Control ofConcrete Mixtures 13 Edition ., Portland Cement Association, Skokie,

I Illinois, (1988)

"Low Cost, No-Care Bridge", Better Roads , (Feb. 1971) p.1 1 .

H "Modern Timber Highway Bridges a State of the Art Report",American Institute of Timber Construction, (1973).

Muchmore, F.W., "Techniques to Bring New Life to Timber Bridges",Journal of Structural Engineering , ASCE , vol 110 (Aug 1984)

Perin, S. "Multi-Plate Arch Bridge Replaces Old One Lane Bridge",Better Roads, (Jan. 1973) p. 20-21.

II

I 79

Peterson, Gary., " Timber Bridges: A Manual To Detail Easily Built,Long-Lasting Structures", Engineering Field Notes, Volume 19, UnitedStates Department of Agriculture, Forest Service (1987)

Pfeifer, Donald W., "Concrete in Systems Bridges", HRB Special Report132: Systems Building for Bridges, Highway Research Board, NationalResearch Council, Washingtion D.C., (1972) pp. 62-65Prestressed Concrete Institute., "Short Span Bridges Spans to 100feet", (1980)

Ritter, Michael A., "Timber Bridges Design, Construction, Inspe ction,and Maintenance", Jun., (1990).

Robison, Rita., "Weathering Steel: Industry's Stepchild"., CivilEngineering Oct., (1988).

Ross, Steven S., Construction Disasters: Design, Failures, Causes, andPrevention, McGraw-Hill Book Co., New York, N.Y., (1984)

I Sack, R.L., "Investigation of Precast and Prestressed Concrete Bridgesfor Low-Volume Roads"., TRB Special Report 160: Low-Volume Roads,Transportation Research Board, National Research Council,Washingtion D.C. (1975) pp 105-115

Sarisley, Edward F., "Construction Methods and Costs of Stress-Laminated Timber Bridges", Journal of Construction Engineering andManagement, ASCE Sept., (1990).

Sprinkle, M. M., "Prefabricated Bridge Elements and Systems." NCHRPReport 119, Transportation Research Board, Washington D. C., (1985).

"The Status of the Nation's Highways and Bridges: Conditions and3 Performance" and "Highway Bridge Replacement and RehabilitationProgram 1989" Report of the Secretary of Transportation to theUnited States Congress June., (1989).

Taly, N.B., and GangaRoa, H.V.S., "Survey of Short Span BridgeSystems in the United States," WVDOH 50-Interim Report 2, CivilEngineering Department, West Virginia University, Morgantown, W.Va. Jan., (1976).

Timber Bridge Information Center, "Crossings", Issue 1, Aug., (1990).

II

I 80

TRB Special Report 202: "America's Highways Accelerating theSearch for Innovation", Transportation Research Board , WashingtonD. C., (1985).

U.S. Steel, Highway Structures Design Handbook Volume 11, (1986).U

3 Virginia Highway and Tranportation Research Council, NCHRP Report222: "Bridges on secondary highways and local roads, rehabilitationand replacement", Transportation Research Board, National ResearchCouncil, Washington D. C., (1980).

3. "Weyerhaeuser Glulam Wood Bridge Systems, Technical Manualabout new and rehabilitated bridges"., Weyerhaeuser Company,(1980).

Williamson, Thomas G., "Steel, concrete, aluminum, and timber insystem bridges.", Highway Research Board Special Reports N132,(1972) ,pp 67-71

IIIIIIl

I

II Appendix A Cover Letter and Stirvey

IUIIUIIIIIIIIIIII

I UNIVERSITY OF WASHINGTONSEATTLE, WASHINGTON 98195

-- Departnent 01 C iil Engineering

September 4, 1990

Dear Sir,

We at the University of Washington (Graduate Program of Construction Engineering andManagement) are conducting a study of short span (less than 120 feet) bridges in counties inIdaho, Oregon, and Washington. The attached survey is focused on materials used in constructionof new short spans. The questions focus on the use of cast in place (CIP) concrete, precastconcrete, steel, and wood. The purpose of the study is to determine the role that various factorsplay in the selection of short span bridge materials.

This survey has been formulated so that it will take an individual familiar with the countybridge program approximately 15-20 minutes to complete. Your participation in the survey isI important for the success of this study. It is important that the survey be returned even if somequestions cannot be answered. !t will be most helpful ii the survey is returned by October 1,

* 1990.

In appreciation of your participation in this study a summary report of this research will beprovided. This report will provide you with information on how other counties are addressingthe replacent of their short span bridges. Your individual responses will be kept confidential.

We would personally like to thank you for taking the time to complete the enclosed survey.

Sincerely,

Jim Hinze John R. Brown

Associate Professor Graduate Student(206)-543-761 2 (206)-742-5605

II

SHORT SPAN BRIDGE SURVEY of IDAHO, OREGON and WASHINGTONCOUNTIES

INFORMATION ABOUT COUNTY BRIDGE PROGRAMCounty Name: State:1) Does the County Public Works Department have a full time bridge engineering staff?2) Number of county engineers assigned full time to bridge program?3) Typically how much is spent annually for bridge: Repair? $

Replacement? $.4) By percentage what have been the sources of funding for replacement?: % County

I_ _% State% Federal

5) What code or codes are used to design new bridges?(AASHTO, State, Other):

INFORMATION ABOUT COUNTY BRIDGESi 6) How many BRIDGES are under your county jurisdiction?

7) How many bridges have AVERAGE DAILY TRAFFIC less than 400 vehicles per day400 - 2000 vehic!es per day

more than 2000 vehicles per day

8) How many BRIDGES, which are predominately of the following materials, require REPLACEMENT?Concrete---> bridgesSteel -.. > bridgesWood -..... > bridges

9) What are the LENGTHS of the bridge-, requiring REPLACEMENT?Less than 30 feet bridges or %30-60 feet ----> bridges or .%60-120 feet---> bridges or %

10) How many new bridges will be made predominately of the following materials?Cast in Place Concree bridges or °/oPre-cast Concrete--> bridges or %Steel ----------- > bridges or %Wood --------.. > ..... bridges or _ %

11) What percentage of new bridges are typically built by the followi-ig sources?Contractor County Crews Other (.

Cast in Place Concrete % % %Pre-cast Concrete--> % % %Steel -----------... . > % %%Wood ----------- > % % %

12) How many new bridges were built or are under construction during 1988-1990 and what are theirlengths? total

Less than 30 feet 30-60 feet 60-120 feetCast in Place Concrete bridges bridges bridgesPre-cast Concrete--> bridges bridges bridgesSteel ----------.... > bridges bridges bridgesWood ------------... > bridges bridges bridges

II

13) What was the AVERAGE COST of new bridges (in $ PER FT of deck surface) for the followingmaterials? LM 18 i9Cast in Place Cc,'crete $_$ $Pre-cast Concrete--> $_$ $Steel ----------- > $. $ $Wood ----------- > $_$ $COMMENTS:

14) Please indicate the number of suppliers of the following bridge materials and proximity to thecounty?

< 10 miles 10 - 100 miles 100 - 200 milesCast in Place ConcretePre-cast Concrete-->Steel -------------- >Wood ------------- >

15) WEIGHT, [FROM 1 (Low Utilization) THROUGH 10 (High Utilization], the USE of the followingI materials in the components of new bridges:Substructure Superstructure Decking

Cast in Place ConcretePre-cast Concrete-->Steel -------------- Wood -------------

3 16) Rate the advantages of Cast In Place Concrete as a bridge material?Disadvantage Neutral Advantage

Simple Design 1 2 3 4 5Familiarity in Department 1 2 3 4 5Material Cost 1 2 3 4 5Material Availability 1 2 3 4 5Initial Construction Cost 1 2 3 4 5Contractor's Familiarity 1 2 3 4 5Speed of Construction 1 2 3 4 5Low Maintenance 1 2 3 4 5Durability 1 2 3 4 5Funding Available (State/Fed) 1 2 3 4 5Aesthetics 1 2 3 4 5Other( ) 1 2 3 4 5COMMENTS:

17) Rate the advantages of Pre-Cast/ Prefabricated Concrete as a bridge material?Disadvantage Neutral Advantage

Simple Design 1 2 3 4 5Familiarity in Department 1 2 3 4 5Material Cost 1 2 3 4 5Material Availability 1 2 3 4 5

Construction Cost 1 2 3 4 5Contractor's Familiarity 1 2 3 4 5Speed of Con,ruction 1 2 3 4 5Low Maintenance 1 2 3 4 5Durability 1 2 3 4 5Funding Available (State/Fed) 1 2 3 4 5Aesthetics 1 2 3 4 5Other( ) 1 2 3 4 5COMMENTS:

I

18) Rate the advantages of Steje as a bridge material?I Disadvantage Neutral Advantage

Simple Design 1 2 3 4 5Familiarity in Department 1 2 3 4 5Material Cost 1 2 3 4 5Material Availability 1 2 3 4 5Construction Cost 1 2 3 4 5Contractor's Familiarity 1 2 3 4 5Speed of Construction 1 2 3 4 5Low Maintenance 1 2 3 4 5Durability 1 2 3 4 5Funding Available (State/Fed) 1 2 3 4 5Aesthetics 1 2 3 4 5Other( ) 1 2 3 4 5

* COMMENTS:

19) Rate the advantages of Engineered Wood as a bridge material?Disadvantage Neutral Advantage

Simple Design 1 2 3 4 5Familiarity in Department 1 2 3 4 5Material Cost 1 2 3 4 5Material Availability 1 2 3 4 5Construction Cost 1 2 3 4 5Contractor's Familiarity 1 2 3 4 5Speed of Construction 1 2 3 4 5Low Maintenance 1 2 3 4 5Durability 1 2 3 4 5Funding Available (State/Fed) 1 2 3 4 5Aesthetics 1 2 3 4 5

Other( ) 1 2 3 4 5* COMMENTS:

20) WEIGHT, [FROM 1 (LEAST important) THROUGH 10 (MOST important], the RELATIVE IMPORTANCEof the following factors in the selection of new bridge MATERIAL:

for SUPERSTRUCTURE: for SUBSTRUCTURE:-FAMILIARITY OF DESIGN-MATERIAL COSTS-MATERIAL AVAILABILITY-CONSTRUCTION COSTS-SPEED OF CONSTRUCTION-MAINTENANCE COSTS-DURABILITY-TOTAL LIFE CYCLE COSTS-REOUIRED BY STATE/FEDERAL FUNDING SOURCE-AESTHETICS-ENVIRONMENTAL IMPACT-OTHER( ) -

If you would like a copy of the summary report, p;, ase provide the following information:(ALL OF YOUR RESPONSES WILL REMAIN CONFIDENTIAL)

Name ---- > TitleAddress---> Telephone->(-)

> _Zip

---> ____Zip_______

I

II Appendix B Summary of Responses

IUIIIIIIIIIIIIIII

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I 134

I Appendix C SPSS Data Definition File and Data File

1

IIII

I

II

III

I include "bridgesl.def".DATA LIST FILE="BRIDGESI.DAT"/COUNTY 1-2 STAFF 4 STAFFNUM 6-7 MONEYRPR 9-12 MONEYRPL 14-17FUNDSCOU 19-21 FUNDSSTA 23-25 FUNDSFED 27-29 CODES 31 NUMBRIDG 33-35I ADTLT400 37-39 ADTBTWN 41-43 ADTGT200 45-47 REPLCONC 49-50REPLSTEE 52-53 REPLWOOD 55-56 REPL30 58-59 REPL60 61-62 REPL120 64-65NEWCIP 67-68 NEWPRE 70-71 NEWSTEEL 73-74 NEWWOOD 76-77I /SUBCIP 1-2 SUBPRE 3-4 SUBSTEEL 5-6 SUBWOOD 7-8SUPERCIP 9-10 SUPERPRE 11-12 SUPERSTE 13-14 SUPERWOO 15-16DECKCIP 17-18 DECKPRE 19-20 DECKSTEE 21-22 DECKWOOD 23-24CIPDESIG 26 CIPFAMIL 27 CIPMATCO 28 CIPMATAV 29 CIPCONST 30I CIPCONTR 31 CIPSPEED 32 CIPMAINT 33 CIPDURAB 34 CIPFUNDI 35CIPAESTH 36/PREDESIG 1 PREFAMIL 2 PREMATCO 3 PREMATAV 4 PRECONST 5PRECONTR 6 PRESPEED 7 PREMAINT 8 PREDURAB 9 PREFUNDI 10PREAESTH 11STEDESIG 13 STEFAMIL 14 STEMATCO 15 STEMATAV 16 STECONST 17STECONTR 18 STESPEED 19 STEMAINT 20 STEDURAB 21 STEFUNDI 22

I STEAESTH 23/WOODESIG 1 WOOFAMIL 2 WOOMATCO 3 WOOMATAV 4 WOOCONST 5WOOCONTR 6 WOOSPEED 7 WOOMAINT 8 WOODURAB 9 WOOFUNDI 10WOOAESTH 11SUPDESIG 13-14 SUPMATCO 15-16 SUPMATAV 17-18 SUPCONST 19-20SUPSPEED 21-22 SUPMAINT 23-24 SUPDURAB 25-26 SUPLIFEC 27-28SUPFUNDI 29-30 SUPAESTH 31-32 SUPENVIR 33-34I SUBDESIG 36-37 SUBMATCO 38-39 SUBMATAV 40-41 SUBCONST 42-43SUBSPEED 44-45 SUBMAINT 46-47 SUBDURAB 48-49 SUBLIFEC 50-51SUBFUNDI 52-53 SUBAESTH 54-55 SUBENVIR 56-57/DUMMY 1-19.

VARIABLE LABELS/STAFF "DOES COUNTY HAVE A FULL TIME STAFF"E /STAFFNUM "NUMBER OF ENGINEERS ON THE STAFF"/MONEYRPR "HOW MUCH IS SPENT ANNUALLY ON BRIDGE REPAIR IN K $/MONEYRPL "HOW MUCH IS SPENT ANNUALLY ON BRIDGE REPLACEMENT IN K $"/FUNDSCOU "SOURCES OF FUNDING % COUNTY"/FUNDSSTA "SOURCES OF FUNDING % STATE"/FUNDSFED "SOURCES OF FUNDING % FEDERAL"/CODES "WHAT CODES ARE USED TO DESIGN NEW BRIDGES?"I /NUMBRIDG "HOW MANY BRIDGES ARE UNDER COUNTY JURISDICTION"/ADTLT400 "# BRIDGES WITH AVERAGE DAILY TRAFFIC LESS THAN 400"/ADTBTWN "#BRIDGES WITH AVERAGE DAILY TRAFFIC BETWEEN 400 AND 2000"/ADTGT200 "#BRIDGES WITH AVERAGE DAILY TRAFFIC GREATER THAN 2000"I /REPLCONC "# CONCRETE BRIDGES THAT REQUIRE REPLACEMENT"/REPLSTEE "# STEEL BRIDGES THAT REQUIRE REPLACEMENT"/REPLWOOD "# WOOD BRIDGES THAT REQUIRE REPLACEMENT"I /REPL30 "# BRIDGES LESS THAN 30 FEET REQUIRING REPLACEMENT"/REPL60 "# BRIDGES BTWN 30 AND 60 FT THAT REQUIRE REPLACEMT"/REPLl20 "# BRIDGES > 60 FT < 120 FT THAT REQUIRE REPLACEMENT"/NEWCIP "# NEW CAST IN PLACE CONCRETE BRIDGES"I /NEWPRE "# NEW PRECAST CONCRETE BRIDGES"/NEWSTEEL "# NEW STEEL BRIDGES"/NEWWOOD "# NEW WOOD BRIDGES"I /SUBCIP TO SUBWOOD "WEIGHT THE USE IN THE SUBSTRUCTURE"/SUPERCIP TO SUPERWOO "WEIGHT THE USE IN THE SUPERSTRUTURE"/DECKCIP TO DECKWOOD "WEIGHT THE USE IN THE DECKING"/CIPDESIG TO CIPAESTH "RATE CAST IN PLACE BRIDGES FOR THE CHARACTERISTIC OF"I /PREDESIG TO PREAESTH "RATE PRE CAST CONCRETE BRIDGES FOR THE CHARACTERISTIC OF"/STEDESIG TO STEAESTH "RATE STEEL BRIDGES FOR THE CHARACTERISTIC OF"/WOODESIG TO WOOAESTH "RATE ENGINEERED WOOD BRIDGES FOR THE CHARACTERISTIC OF"I /SUPDESIG TO SUPENVIR "WEIGHT THE RELATIVE IMPORTANCE FOR SUPERSTRUCTURES"/SUBDESIG TO SUBENVIR "WEIGHT THE RELATIVE IMPORTANCE FOR SUBSTRUCTURES".

I

MISSING VALUE/STAFF(9) STAFFNUM TO FUNDSFED (99) CODES (9)NUMBRIDG TO DECKWOOD (99) CIPDESIG TO WOOAESTH (9)SUPDESIG TO SUBENVIR (99).

j VALUE LABELS/STAFF 1 "NO" 2 "YES"/CODES 1 "AASHTO" 2 "STATE" 3 "AASHTO and STATE" 4 "COUNTY" 5 "FHWA"

* /SUBCIP TO DECKWOOD 1 "LOW UTILIZATION" 10 "HIGH UTILIZATION "/CIPDESIG TO WOOAESTH 1 "DISADVANTAGE" 3 'NEUTRAL' 5 "ADVANTAGE"/SUPDESIG TO SUBENVIR I "LEAST IMPORTANT" 10 "MOST IMPORTANT".

I

aa

ERROR 1, Text: AAINVALID COMMAND--Check spelling. If it is intended as a continuation of aprevious line, the terminator must not be specified on the previous line.If a DATA LIST is in error, in-line data can also cause this error.This command not executed.

SPSS/PC+

This procedure was completed at 15:00:07set printer off.01 1 00 0015 0075 050 030 020 1 138 132 006 000 05 05 15 04 03 18 00 25 00 00100101010110010101100101 5555459443355454454433 2222222232244424342214 1009100910070908080105 1009100910090910080105

02 1 00 0014 0100 020 000 080 2 015 013 001 001 01 03 00 01 03 99 00 02 00 02100101010210010105050101 3534252454345334455443 3233334455432434243455 0510091008090809100908 0710091008101010100508

03 1 01 0035 0200 020 000 080 1 056 030 020 006 01 01 06 04 03 01 00 08 00 00100401010110010108080101 1515252443435554554434 2124232124431252421145 1005061010101010050105 1010100810101010050505

04 1 00 0050 0500 025 000 075 1 042 025 014 003 02 04 00 00 04 02 00 06 00 00080299990109999902089999 2234432333354433453333 2232333233322323231133 0504060607090810050302 0504060607080910050302

05 1 00 0000 0200 040 000 060 1 041 015 025 001 01 03 02 00 02 02 00 04 00 02100005050108020601080006 3435341333344343453332 1132333113355333453234 0909070909080805010505 0906050707070705010105

06 1 01 0099 0099 025 000 075 1 069 028 029 012 02 01 02 00 03 02 00 05 00 00070701010806010107050101 4435343444332334344443 3223232143343433342223 0507080805070707070505 0507080805070707070505

07 1 00 0020 0100 020 000 080 1 065 065 000 000 01 00 12 00 13 00 00 13 00 00109999999910999999109999 5444444444399999999999 99999999999

-- 99999999999 9999999999999999999999 9999999999999999999999

08 1 00 0050 0200 050 000 050 3 060 044 008 008 00 00 01 00 00 01 00 00 01 00100105019999999999999999 3434332553344343345533 3333334343333233242233 0510101005101010050506 0509101005101010050106

09 1 00 0003 0075 020 000 080 2 014 010 004 000 01 02 00 00 00 03 00 03 00 00060499990401990503039905 3123233453431444344534 3333121142331554342234 0208061003070409010305 0208061003070409010305

10 2 15 0030 0600 025 000 075 3 152 100 042 010 02 05 10 04 05 08 00 17 00 00100309050910010110090101 5555341553555544444434 5333234233355554452233 1005081008101010100505 1005081008101010100505

11 9 99 0099 0099 099 099 099 9 099 099 099 099 99 99 99 99 99 99 99 99 99 99999999999999999999999999 9999999999999999999999 9999999999999999999999 9999999999999999999999 9999999999999999999999

12 1 00 0010 0565 020 000 080 5 024 010 011 003 99 99 99 99 99 99 99 99 99 99050005009910999999109999 9999999999955334444453 9999999999999999999999 0808080506080805030308 9999999999999999999999I

I

SPSS/PC+

This procedure was completed at 15:00:07set printer off.01 1 00 0015 0075 050 030 020 1 138 132 006 000 05 05 15 04 03 18 00 25 00 00100101010110010101100101 5555459443355454454433 2222222232244424342214 1009100910070908080105 1009100910090910080105

02 1 00 0014 0100 020 000 080 2 015 013 001 001 01 03 00 01 03 99 00 02 00 02OnljO!02lC.10!050rO!n1 3514?525i3

45334455443 3233334455432434243455 0510091008090809100908 0710091008101010100508

03 1 01 0035 0200 020 000 080 1 056 030 020 006 01 01 06 04 03 01 00 08 00 00100401010110010108080101 1515252443435554554434 2124232124431252421145 1005061010101010050105 1010100810101010050505

04 1 00 0050 0500 025 000 075 1 042 025 014 003 02 04 00 00 04 02 00 06 00 00080299990109999902089999 2234432333354433453333 2232333233322323231133 0504060607090810050302 0504060607080910050302

05 1 00 0000 0200 040 000 060 1 041 015 025 001 01 03 02 00 02 02 00 04 00 02

100005050108020601080006 3435341333344343453332 1132333113355333453234 0909070909080805010505 0906050707070705010105

06 1 01 0099 0099 025 000 075 1 069 028 029 012 02 01 02 00 03 02 00 05 00 00070701010806010107050101 4435343444332334344443 3223232143343433342223 0507080805070707070505 0507080805070707070505

07 1 00 0020 0100 020 000 080 1 065 065 000 000 01 00 12 00 13 00 00 13 00 00109999999910999999109999 5444444444399999999999 9999999999999999999999 9999999999999999999999 9999999999999999999999

08 1 00 0050 0200 050 000 050 3 060 044 008 008 00 00 01 00 00 01 00 00 01 00100105019999999999999999 3434332553344343345533 3333334343333233242233 0510101005101010050506 0509101005101010050106

09 1 00 0003 0075 020 000 080 2 014 010 004 000 01 02 00 00 00 03 00 03 00 00060499990401990503039905 3123233453431444344534 3333121142331554342234 0208061003070409010305 0208061003070409010305

10 2 15 0030 0600 025 000 075 3 152 100 042 010 02 05 10 04 05 08 00 17 00 00100309050910010110090101 5555341553555544444434 5333234233355554452233 1005081008101010100505 1005081008101010100505

11 9 99 0099 0099 099 099 099 9 099 099 099 099 99 99 99 99 99 99 99 99 99 99999999999999999999999999 9999999999999999999999 999999999991 99999999999 9999999999999999999999 9999999999999999999999

12 1 00 0010 0565 020 000 080 5 024 010 011 003 99 99 99 99 99 99 99 99 99 99050005009910999999109999 9999999999955334444453 9999999999999999999999 0808080506080805030308 9999999999999999999999

13 2 10 0099 0099 050 000 050 1 195 099 099 099 02 10 03 04 05 06 04 06 02 01099901010999080109990801 2335151549355311349292 5324232259542323334195 1010101008080810991099 0810101010101008990899

14 1 00 0010 0100 099 099 099 3 025 099 099 099 20 00 05 01 04 00 00 05 00 00089999999910999999999999 3334242443343244455444 9999999999954444341222 9999999999999999999999 9999999999999999999999

I1 00 uo 0275 025 uou u05 9 22U 100 110 010 99 99 99 99 99 99 99 99 99 99999999999999999999999999 4434232443343444355544 2222232233344555352111 0507050705091010100505 0507050705091010100505

16 1 00 0005 0150 020 000 080 1 063 063 000 000 00 10 00 00 00 10 05 05 00 00100199990604999909029999 4333432444333333454443 3233223232333444332223 0108050903070502100406 0108050903070502100406

17 2 10 0099 0200 050 000 050 1 213 134 070 009 03 07 03 03 03 07 00 13 00 00100105011010999910109903 5455434554355554455454 3133313113354333121121 0505100509101010050501 0509050909101009050501

18 1 01 0099 0099 020 000 080 1 135 134 001 000 05 16 04 06 15 04 00 25 00 00100101010310040101011001 5555555555355555555555 4234425555452333212355 0810101008101005050507 0810101008101005050507

19 1 00 0020 0300 020 000 080 1 063 061 002 000 00 03 16 03 04 12 07 12 00 00100505011005050110100101 5555355555353545555555 1111111111111435222224 0505050505101010100505 0505050505101010100210

20 1 00 0003 0000 050 050 000 2 013 013 000 000 00 00 00 00 00 00 00 00 00 00100501011010070310109999 4535343554355343355433 2223333233345553331133 1008080806080806100506 1008080806080806100506

21 2 20 0099 0099 020 000 080 1 126 053 041 032 02 04 04 00 02 00 00 09 01 00100000021010020210050003 3333333553334333455533 2222224233343344342333 0810101008101010050710 0810101008101010050710

22 1 00 0001 0000 000 000 000 2 003 001 001 001 02 00 00 02 00 00 00 00 00 02999999109999991099999910 5135322555221111144443 2123213244241444444444 0709090910101009051010 0809090910101008061010

23 1 00 0140 0040 020 000 080 1 091 041 040 010 02 00 03 02 02 01 00 05 00 00080501010510010110050101 4334241333523323252332 2123224123453444342234 0809080806101010050805 0610090806101010050805

24 2 03 0650 2000 020 000 080 3 190 099 099 099 04 08 27 03 03 09 02 38 00 00999999999999999999999999 4434232453344343434543 2322234234322333342234 0607071005101005080508 0607071005101005080508

25 1 00 0225 0550 020 000 080 3 102 030 048 024 60 24 18 03 01 07 03 08 00 00100101011010010110060101 3355552553533323455534 3243324113333544341133 0105050805101010100608 0105050805101010100608

26 1 00 0050 0700 010 090 080 3 320 300 020 000 70 10 50 40 20 20 00 75 00 05090105030109010301090103 1113121555544343444444 4114234334343333454444 0510060907080403060201 0510060907080403060201

27 1 00 0000 0000 020 000 080 2 086 086 000 000 00 02 04 00 05 00 00 06 00 00999999999999999999999999 2425232443354555555555 4533345453314121431112 0910090908101010100706 0810080802100810100506

28 1 00 0060 0080 100 000 000 1 112 078 022 012 00 01 07 01 04 03 00 06 01 01011010010710080909109908 2335353441523555555515 4335455551355545353355 0510081008101005050505 0510081008101005050505

29 1 99 0015 0200 040 010 050 1 070 050 018 002 02 00 15 03 10 02 00 15 00 00109901999910999999999999 3333333333343333343333 2224333133333344321132 9907060704100910090303 9907060704100910090303

30 1 00 0354 1500 075 005 020 1 300 180 160 027 01 06 24 09 11 06 00 31 00 00090209060809060508090506 2425332323454544554432 3533222143334454442234 0806070809091008060707 0808070809070909070708

31 1 00 0002 0000 010 020 070 9 018 018 000 000 13 03 02 00 00 18 00 18 00 00109999999910999999109999 33112424453I43443444444 3344344334333453242213 0107070710020410080101 0107070706020410080101

32 1 00 0050 0000 025 025 050 2 039 039 000 000 01 00 00 00 00 01 00 01 00 00101008081010080810100808 53353555544--: 55335555553 3433343335334453333353 0505050508080808060505 0505050508080808060505

33 1 00 0005 0030 005 005 080 1 018 012 006 000 00 00 01 01 00 00 99 99 99 99999999999999999999999999 1134332443331313144433 3231313223333343443233 0503020305101010100305 0503020305101010100308

34 1 00 0015 0060 010 010 080 1 165 145 018 002 00 01 02 99 99 99 01 03 00 00100000009909000009099999 5544452333355343555555 4232344444442244342234 0810090907101010070408 0910090506101010050408

35 2 50 1500 0000 010 010 080 1 042 005 008 029 00 01 01 00 01 00 01 01 00 00999999999999999999999999 4435253444353454353333 5533355123351334352324 9905090410060701020803 9905090410060701020703

36 1 01 0099 0099 099 099 199 1 140 070 070 005 00 00 35 21 07 07 00 31 02 02999908999910999999109999 1113111333355555553333 1133333133331333133333 0505050505050505030303 0505050505050505030303

37 1 00 0100 0450 094 003 003 3 091 058 032 001 00 05 12 03 06 03 00 27 00 00040105000003020001070002 1233232554354342455543 3333334234312322221139 9999999999999999999999 9999999999999999999999

38 1 00 0030 0100 090 005 005 3 350 332 145 004 00 01 25 68 10 06 00 00 42 42100706050607100506071005 5335352553353442525554 55353355534

II

55353331339 0508081010101010050510 0508081010101010050510

39 1 00 0040 0000 100 000 000 2 089 060 024 005 01 01 40 25 08 09 99 99 99 99999999999999999999999999 4233234553332333445533 1133332233231332331135 0306051002090708990104 0205041003090807990106

40 1 00 0099 0099 099 099 099 9 052 000 052 000 00 08 04 00 00 12 99 99 99 99999999999999999999999999 5553451553435534555534 55135342332R 5c539235 0508080805100810050602 05090809051009]0050703

41 2 01 0050 0075 010 010 080 2 080 060 019 001 00 00 10 06 03 01 01 09 00 00091001010910010109100101 3344344445455555355534 3333332223433333322234 06040507080903100 0199 9999999999999999999999

42 1 00 0200 0600 008 012 080 2 134 097 035 002 00 00 02 02 00 00 00 02 00 00011001010110010101100101 3333333333345443455545 33333333333i 33333333333 0807030706080709010101 0601040703010604010101

43 1 00 0005 0003 000 100 000 1 041 027 014 000 00 01 05 00 04 02 00 06 o no049999999999999999109999 3344333233233254455523 9999999999999 99999999 0509100909070807100399 0509100909070807100399

44 1 99 0099 0099 099 099 099 9 042 040 0U2 000 00 00 05 02 02 01 01 04 00 00109999990799999910999999 9555991559955359955599 99q9999999999999999999 1099109908991010999999 1099109910991010999999

45 1 00 0015 0035 010 015 075 1 100 065 025 010 25 05 05 23 09 05 00 25 10 00999999999999999999999999 5344443343343223344444 9999999999999999999999 0606060608050505060606 0606060608050505060606

46 9 99 0099 0099 099 099 099 9 000 099 099 099 99 99 99 99 99 99 99 99 99 99999999999999999999999999 99999999999i 99999999999 99999999999

I9999999999999999999999999999999999999999999999999999999

47 1 00 0040 0000 050 050 000 1 035 015 020 000 04 15 01 00 05 15 00 05 15 00999999999999999999999999 9999999999955555555535 5534333443451115151135 1010101010101010000110 1010101010101010000110

i 48 1 00 0012 0099 020 080 000 1 071 061 010 000 00 01 02 02 00 01 00 01 00 02100000020110010204080008 9999999999995999945999 99999999999I99999999999 9999999999999999999999 999999999999999999999949 1 99 0099 0099 099 099 099 3 056 033 020 003 00 02 07 01 03 05 00 09 00 00999999999999999999999999 344435144431 54433555545 1111111111199999999999 9999999999999999999999 9999999999999999999999

50 1 00 0075 0060 100 000 000 2 018 013 005 000 04 04 12 03 02 01 00 01 00 05090309030703030707030804 4444532251232433343312 4444444441223244342315 0709051008070708010409 0709051008070708010409

* 51

II

1* AppendixDList of Respondents

IIIIIIIIIIIIIIIII

Appendix D List of Respondents

SPSS County Name Address City State ZipNumber

1 Adams County, WA Walt Olsen 210 W. Broadway Ritzville, WA. 991692 Asotin Cnunty, WA Richard Weaver, PI P.O. Box 160 Asotin, WA. 994023 Benton County, WA Dennis Skeate, PE P.O. Box 110 Prosser, WA. 993504 Chelan County, WA Lloyd Berry, PE/L: Courthouse, Wenatc Wenatchee, WA. 988015 Clallam County, WA Don Mclnnes 223 E. 4th Port Angeles, WA. 983626 Columbia County, WA Gary Gasaway, PE 341 E. Main St. Dayton, WA. 99328U 7 Cowlitz County, WA Kenneth C. Stone 207 N. 4th Kelso, WA. 986268 Ferry County, WA Greg Pezoldt, Eng - P.O. Box 344 Republic, WA. 991669 Grays Harbor, WA Russ Esses P. 0. Box 511 Montesano, WA 9856310 Island County, WA Roy Allen, PE Box 5000 Coupeville, WA 9823911 Jefferson County, WA Bruce Laurie P.O. Box 1220 Port Townsend, WA 9836812 King County, WA Doug Mattoon, PE 500 4th Avenue Seattle, WA 98104I 13 Kitsap County, WA David E. Dickson, 614 Division Port Orchard, WA 9836614 Kittitas County, WA John Nixon 205 W.5th, Room 1 Ellensburg, WA 9892615 Klickitat County, WA Ed Hoyle, PE 205 So. Columbus Goldendale, WA 98620I16 Lewis County, WA Darrel 0. McMurpP P.O. Box 899 Chehalis, WA. 9853217 Lincoln County, WA Glen Oliver, PE Box 368 Davenport, WA 9912218 Pacific County, WA John Bay Box 66 South Bend, WA 98586

19 Pend Oreille County, W Michael Rabe, PE P.O. Box 5000 Newport, WA 9915620 Pierce County, WA Don Peterson, P.E. 2401 So. 35th Tacoma, WA 98409-748721 Sar County, IWA David 0' Kane Box 729 Friday Harbor, WA 98250

22 Skagit County, WA Chet Reid Rm 203 Co. Admin. Mt. Vernon, WA 9827323 Snohomish County, WA Darrell Ash, PE 2918 Colby Street Everett, WA 9820124 Thurston County, WA Dale Rancour 2000 Lakeridge Dr. Olympia, WA 9850225 Whitman County, WA Lon R. Pedersen P.O. Box 430 Colfax, WA 9911126 Baker County, OR William S. McHane 3050 E Street Baker City, OR 9781427 Benton County, OR Roger Irvin, Assist 360 S.W Avery Av Corvallis, OR 9733328 Clatsop County, OR Randy Trevillian 1100 Olney Ave. Astoria, OR 9710329 Douglas County, OR Morrie Chappel 219 County Courthc Roseburg, OR 9747030 Gilliam County, OR John Russum P.O. Box 427 Condon, OR 9782331 Grant County, OR Doug Kruse P.O. Box 190 Canyon City, OR 9782032 Hood River County, OR James F. Lyon, Di 918 18th Street Hood River, OR 97031

33 Malheur County, OR Ray Stooks, Bridg, 251 'B' St. West, B. Vale, OR 97913-135734 Multnomah County, OR Stan M. Ghezzi, P.E 1629 S.E. 190th Portland, OR 9723335 Polk County, OWayne L. Rickert Jr., Director 206 County Courthc Dallas, OR 97338

36 Tillamook County, OR Jon Oshel, Directo 503 Marolf Loop Tilamook, OR 97141

37 Umatilla County, OR Ivan E. Pointer 3920 Westgate Pendleton, OR 9780138 Union County, OR Richard Comstock P.O. Box 1103 La Grande, OR 97850

39 Wallowa County, OR Merlin 'Skip' Lovel P.O. Box 219 Enterprise, OR 9782840 Wasco County, OR Daryl Ingebo, Bride County Courthouse, The Dalles, OR 9705841 Yamhill County, OR Dan Linscheid 2060 Lafayette AvE McMinnville, OR 97128

42 Lewis County, ID Director of County Lewis County Cour Nezperce, ID 8354343 Jim Stackhouse Box 1418 Bonner's Ferry, ID 83805I

I

Appendix D List of Respondents

SPSS County Name Address City State ZipNumber

44 Fremont County, ID Lyle I. Thompson 215 Farnsworth WE Rigby, ID 83442

45 Shoshone County, ID Shoshone County Drawer A Shoshone, ID 8335246 Nez Perce County, ID R.N. Flowers Couni 805 26th St North Lewiston, ID 83501

47 Canyon County, ID48 Mason County, ID Elden L. Reed P.O. Box 357 Shelton, WA 9858449 Clark County, WA Brian Vincent, PE P.O. Box 5000 Vancouver, WA. 98668

50 Boise County, ID Director of Public P. 0. Box 156 Idaho City, ID 83631

I;I

I

I3 Appendix E Summary of Costs for New Bridges

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